At Dish RCP, we believe that great recipes come from bold experimentation—and there’s no better example of that than these sourdough peanut butter brownies. This twist on the classic brownie uses sourdough discard for extra depth and moisture, all while swirling in creamy peanut butter for a melt-in-your-mouth finish. Whether you’re trying to reduce food waste by repurposing your discard or you’re just craving a next-level dessert, this recipe delivers fudgy, rich results every time.
In this article, we’ll walk you through the best practices, benefits, baking techniques, and storage tips for mastering sourdough peanut butter brownies. Plus, we’ll answer popular questions like “Can I use brownie mix?” and “Are these healthy?” along the way.
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Table of Contents
Table of Contents
Why Make Sourdough Peanut Butter Brownies?
What Makes These Brownies Unique
Unlike typical brownies made with just flour, sugar, and cocoa, sourdough peanut butter brownies bring a unique depth of flavor, thanks to the tangy richness of the fermented sourdough discard. This slight tanginess contrasts the sweetness and makes the chocolate flavor even more intense.
The Role of Sourdough Discard in Desserts
Using sourdough discard in baked goods reduces waste and adds tenderness. The natural acidity helps break down starches and proteins in the batter, resulting in a moist, dense texture. These aren’t your average dry brownies—they’re thick, gooey, and unforgettable.
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Sourdough Peanut Butter Brownies
- Total Time: 40 minutes
Description
These lunchbox-style sourdough peanut butter brownies are rich, fudgy, and packed with flavor. Made with a chocolatey sourdough batter and swirled with creamy peanut butter, they bake up into a decadent treat perfect for snacking or packing in a lunchbox.
Ingredients
- 113 grams unsalted butter, melted and warm, 1/2 cup
- 140 grams brown sugar, 2/3 cup, packed
- 140 grams white sugar, 2/3 cup
- 85 grams chopped dark chocolate, melted, 3 oz
- 2 large eggs, 100 grams
- 100 grams sourdough discard, scant 1/2 cup
- 4 grams vanilla extract, 1 teaspoon
- 55 grams cocoa powder, dark or dutched, 2/3 cup
- 30 grams all-purpose flour, scant 1/4 cup
- 6 grams salt, about 1 teaspoon
- 85 grams creamy peanut butter, about 1/3 cup
Instructions
Preheat your oven to 350ºF (175ºC). Line an 8×8-inch metal baking pan with parchment paper.
In a large mixing bowl, whisk together the melted butter, brown sugar, and white sugar.
Melt the dark chocolate in a microwave-safe bowl, stirring every 20–30 seconds to avoid burning. Once melted, whisk it into the butter-sugar mixture.
Add the eggs one at a time, whisking well after each addition. Stir in the sourdough discard and vanilla extract until fully combined.
Add the cocoa powder, flour, and salt directly on top of the wet mixture. Use a spatula to fold everything together until the batter is smooth and thick.
Pour the brownie batter into the prepared pan and spread it evenly.
Drop 9 small spoonfuls of creamy peanut butter across the top. Use a knife to gently swirl the peanut butter through the batter.
Bake for 35–40 minutes, or until the edges and top are set. Avoid overbaking—check with a toothpick; it should come out with moist crumbs, not clean. For extra precision, the center should reach about 190ºF.
Let the brownies cool completely in the pan before slicing into squares.
Serve and enjoy!
Notes
Sourdough Discard: Use discard that’s no more than a few days old to avoid an overly tangy flavor. Older discard will produce a stronger sour taste in the brownies. This recipe uses 100% hydration sourdough discard.
Brownie Texture: Bake time impacts texture—longer baking results in a cakier brownie. For a fudgy texture, aim for an internal temperature of 190ºF. For cakier brownies, bake until the center reaches up to 210ºF.
Peanut Butter: Stick with a no-stir, creamy peanut butter for best results. Natural varieties with separated oil don’t incorporate as well and can affect the texture of the baked brownies.
- Prep Time: 15minutes
- Cook Time: 25minutes
- Category: Baking, Side Dish, Sides
- Cuisine: American
Nutrition
- Serving Size: 16 brownies
- Calories: 211kcal
- Sugar: 19g
- Sodium: 182mg
- Fat: 12g
- Saturated Fat: 6g
- Unsaturated Fat: 4g
- Trans Fat: 0.2g
- Carbohydrates: 26g
- Fiber: 2g
- Protein: 3g
- Cholesterol: 39mg
Key Ingredients for Sourdough Peanut Butter Brownies
Understanding Each Component in the Recipe
To bake the perfect sourdough peanut butter brownies, every ingredient must play its role precisely. Here’s a breakdown of what each does in this rich dessert:
- Butter (113g, melted): Adds fat and flavor, helping create a rich and tender crumb.
- Brown Sugar (140g) + White Sugar (140g): Combines caramel depth and sweetness, key for chewy texture.
- Melted Dark Chocolate (85g): Gives these brownies their bold, fudgy base.
- Eggs (2 large): Provides structure, richness, and a luscious bite.
- Sourdough Discard (100g): Adds moisture and a subtle tang without overpowering.
- Vanilla Extract (4g): Enhances chocolate and peanut butter flavors.
- Dark Cocoa Powder (55g): Intensifies the chocolate flavor and helps thicken the batter.
- Flour (30g): A minimal amount to maintain fudginess, not cakey texture.
- Salt (6g): Balances sweetness and elevates flavor layers.
- Creamy Peanut Butter (85g): Swirled in for a smooth, nutty counterbalance to the deep cocoa.
Ingredient Substitutions and Tips
- Butter Substitute: You can use browned butter for a nuttier flavor or plant-based butter for a dairy-free option.
- Chocolate Swaps: Try bittersweet chocolate for less sugar or milk chocolate for a milder taste.
- Sourdough Tips: Use discard that’s no more than 4 days old to avoid excessive tang.
- Peanut Butter Note: Avoid natural peanut butter with separated oils—it won’t swirl well and affects texture. Use no-stir varieties instead.
How to Make Sourdough Peanut Butter Brownies the Right Way
Mixing the Batter Step-by-Step
Making sourdough peanut butter brownies at home is easier than you think—but getting that dense, fudgy texture depends on how you mix and bake your ingredients. Let’s break it down step-by-step:
- Preheat and Prepare
Set your oven to 350°F. While it heats up, line an 8×8 metal baking pan with parchment paper. Using metal ensures even baking and that crisp edge brownie lovers crave. - Combine Butter and Sugars
In a large mixing bowl, whisk together the warm, melted butter with both brown and white sugar. This base helps create a chewy bite and sweet caramel undertone. - Melt and Mix in Chocolate
Gently melt the dark chocolate in the microwave, pausing every 20–30 seconds to stir. Once smooth, mix it into the sugar-butter blend. This melted chocolate adds rich depth to your sourdough brownies. - Add Eggs, Discard, and Vanilla
Crack in the eggs one by one, mixing until fully blended. Mix in the sourdough discard and vanilla extract until fully blended and smooth. This step creates the glossy, thick texture that forms the base of these brownies. - Incorporate Dry Ingredients
Add the cocoa powder, flour, and salt directly into the bowl. Use a spatula—not a mixer—to gently fold everything together until no dry streaks remain. Be careful not to overmix, or you’ll lose that gooey center.
Swirling and Baking for the Best Texture
Here’s where the peanut butter magic happens.
- Add the Batter to the Pan
Pour your thick chocolate batter into the prepared pan and spread it evenly across all corners. - Swirl the Peanut Butter
Drop small spoonfuls of creamy peanut butter on top—about 9 scattered dollops. Use a butter knife or skewer to lightly swirl the peanut butter into the surface without blending it completely. This gives the brownies their marbled finish and nutty punch. - Bake to Fudgy Perfection
Slide the pan into the oven and bake for 35 to 40 minutes. You’re aiming for set edges and a slightly soft center.
To get that ultra-fudgy consistency, use a thermometer and pull them out at 190°F. Want something cakier? Let them go a few minutes longer to reach 210°F. - Cool Completely Before Slicing
This part is key—allow your brownies to cool fully in the pan before slicing into squares. Cutting too early will make them crumble and lose structure.
Unlocking the Texture and Flavor Secrets in Sourdough Peanut Butter Brownies
Why Sourdough Discard Makes a Difference
Sourdough discard is more than a waste-saving bonus—when used in baking, it completely transforms texture. In sourdough peanut butter brownies, the discard adds moisture while relaxing the gluten in flour, resulting in a softer, chewier bite. Unlike traditional brownie recipes that may lean dry or overly dense, these come out rich and fudgy every time.
The natural acidity from the starter also brings balance to the sweetness, letting the chocolate and peanut butter flavors stand out without being cloying. So instead of a flat chocolate block, you’re getting layers of flavor and perfect bite resistance.
How Ingredients Work Together
Each ingredient in sourdough peanut butter brownies plays a key role. Cocoa powder and melted chocolate build the chocolate base—one gives intensity, the other adds smoothness. Butter plays the role of a carrier, bringing everything together and delivering that classic gooey texture we all crave.
Peanut butter doesn’t just swirl for looks. It breaks up the richness of the chocolate and gives the brownies a creamy, nutty contrast. Combined with the discard’s tang, it creates a treat that’s both indulgent and surprisingly balanced.
Taste Layers: Not Just Sweet, But Complex
Brownies made with discard don’t scream “sour.” Instead, they offer a subtle sharpness that cuts through the sugar, enhancing the cocoa’s deeper notes. With every bite of these sourdough peanut butter brownies, you taste a little sweetness, a little salt, a lot of chocolate, and just enough tang to make you reach for another piece.
That complexity is why these brownies feel elevated, even if the recipe is simple. It’s not just a dessert—it’s a crafted experience in flavor layering.
How to Swirl Peanut Butter Perfectly in Sourdough Peanut Butter Brownies
Selecting the Best Peanut Butter for Swirling
To create eye-catching swirls in your sourdough peanut butter brownies, the type of peanut butter you use really matters. Go for a smooth, no-stir peanut butter—the kind that doesn’t separate. These hold up better during baking, keeping your swirl patterns clear and consistent across the top of the brownie layer.
If you use a natural peanut butter that tends to separate, the oils may rise or bake unevenly, making the swirl look messy or sink into the batter. For clean ribbons of flavor, a creamy, well-blended spread is your best choice.
Simple Steps to Swirl Like a Pro
Getting perfect peanut butter swirls in your sourdough peanut butter brownies doesn’t require fancy tools. Here’s the easiest way to do it:
- After spreading your chocolate batter evenly in the baking pan, drop small spoonfuls of peanut butter evenly across the surface—about 9 spaced-out dollops work well.
- Drag a toothpick, skewer, or butter knife through the peanut butter to create smooth, even swirls. Swirl gently in curves or figure-eights to create a marbled pattern.
- Don’t overdo it. Light swirling keeps the design clear and allows the peanut butter flavor to shine without blending completely into the batter.
Avoiding Common Swirling Mistakes
If your swirl disappears during baking, chances are your peanut butter was too runny or overworked. You want it soft, but not melted. If it’s too firm to scoop, microwave it for just a few seconds to soften.
Also, avoid swirling too deep into the batter. Surface-level swirling ensures that your sourdough peanut butter brownies bake with distinct layers of flavor and visual appeal.
Best Tools and Bakeware for Sourdough Peanut Butter Brownies
Why Your Pan Choice Matters
When baking sourdough peanut butter brownies, the type of pan you use can make or break the final result. A metal baking pan is your best bet. It conducts heat evenly, helping the edges cook properly while leaving the center soft and gooey—exactly what you want in a rich, fudgy brownie.
Glass and ceramic pans, while fine for other baked goods, tend to heat slower. This often results in undercooked centers or overbaked edges. Stick with an 8×8-inch metal pan lined with parchment paper for the most consistent, clean outcome.
Must-Have Tools for Better Brownies
To elevate your sourdough peanut butter brownies, make sure you’re working with the right baking tools. Here are some key items that’ll help things go more smoothly and improve your outcome:
| Tool | Purpose |
|---|---|
| Large mixing bowl | To blend all wet and dry ingredients efficiently |
| Rubber spatula | For folding batter and scraping the bowl clean |
| Offset spatula | Helps spread batter evenly into corners of the pan |
| Microwave-safe bowl | For safely melting chocolate |
| Digital kitchen scale | Ensures precise ingredient measurements |
| Toothpick or skewer | To check doneness and swirl the peanut butter cleanly |
Quality tools aren’t just nice to have—they help guarantee even baking, smoother mixing, and that professional finish in your sourdough peanut butter brownies.
Optional but Useful Upgrades
- Oven thermometer: Most ovens run hot or cold—an accurate reading can prevent overbaking.
- Brownie divider: Want perfectly even portions? A divider insert gives clean, bakery-style squares.
- Digital probe thermometer: Check the internal temperature (190ºF) for ideal fudginess without guessing.
How to Store and Freeze Sourdough Peanut Butter Brownies
Store Brownies the Right Way
To keep your sourdough peanut butter brownies soft and fresh, let them cool completely before storing. Place them in an airtight container and separate layers with parchment paper if needed. Stored at room temperature, they remain moist for 3 to 4 days due to the added hydration from the sourdough discard.
Refrigeration Tips
If you’re keeping your sourdough peanut butter brownies for a week or longer, refrigeration works well. Wrap each square in plastic wrap, then place in a sealed container. This helps maintain the texture and prevents them from drying out.
How to Freeze for Later
Freezing is ideal when you want to enjoy sourdough peanut butter brownies at a later time. Here’s how:
- Allow the brownies to cool fully.
- Wrap each piece in plastic wrap, then add a layer of foil.
- Place in a freezer-safe container or bag.
Frozen sourdough peanut butter brownies will hold up for about 2–3 months. Thaw them in the fridge or warm them slightly before eating for best texture.
Nutritional Facts and Health Considerations of Sourdough Peanut Butter Brownies
What’s Inside Each Bite?
Sourdough peanut butter brownies are rich, indulgent, and surprisingly more balanced than your average brownie. Every square delivers a balanced mix of carbs, healthy fats, and a touch of protein. The sourdough discard adds moisture without more oil or butter, which helps reduce the need for extra fat.
Here’s a general estimate for one square (based on 16 servings):
| Nutrient | Estimated Amount |
|---|---|
| Calories | 180–210 kcal |
| Total Fat | 10–12g |
| Sugar | 15–18g |
| Protein | 3–4g |
| Fiber | 1–2g |
These values will vary slightly based on the peanut butter brand and chocolate used.
How Sourdough Adds a Health Edge
Using sourdough discard offers more than texture—it may aid digestion for some people. The discard comes from a fermented starter, which contains organic acids and natural bacteria. While most of the microbes die during baking, the acidity can help reduce the glycemic load slightly and enhance mineral absorption.
Compared to traditional brownies, sourdough peanut butter brownies may have:
- A slightly lower sugar spike
- Better moisture retention without added oil
- A more satisfying bite, meaning you’re less likely to overeat
Balance and Moderation
Of course, sourdough peanut butter brownies are still a treat. They contain sugar, fat, and chocolate—but using real ingredients like sourdough discard and natural peanut butter means you’re baking something more wholesome than boxed mixes or store-bought desserts.
Why Sourdough Peanut Butter Brownies Deserve a Spot in Your Recipe Box
If you’re ready to take brownies to the next level, sourdough peanut butter brownies are a must-try. They’re rich, chewy, deeply chocolatey, and balanced with creamy swirls of peanut butter. Best of all, they reduce waste by putting your sourdough discard to delicious use.
Whether you’re baking for friends or just craving a unique homemade treat, these brownies deliver something unforgettable in every bite.
FAQs About Sourdough Peanut Butter Brownies
Can I make sourdough peanut butter brownies using a boxed brownie mix?
Yes! If you’re short on time, you can absolutely use a store-bought mix. Prepare the brownie mix according to package instructions, then fold in about ½ cup of sourdough discard and swirl in peanut butter before baking. It won’t be quite as rich as homemade, but you’ll still get that signature tang and creamy swirl that defines sourdough peanut butter brownies.
Are sourdough peanut butter brownies easy to make?
Absolutely! Despite their gourmet name, the process is straightforward—just mix your wet and dry ingredients separately, blend them together, swirl in some peanut butter, and pop them in the oven.
Even if you’re new to baking, you can whip up these brownies using basic kitchen tools and common pantry staples.
Are sourdough peanut butter brownies easy to make?
Definitely. While they sound fancy, the steps are simple. You mix the wet and dry ingredients separately, combine them, swirl in peanut butter, and bake. Even beginners can successfully make sourdough peanut butter brownies with basic tools and pantry ingredients.
Are sourdough peanut butter brownies healthy?
While they’re still a dessert, these brownies use whole ingredients like natural peanut butter and sourdough discard, which adds moisture and slight nutritional benefits. Compared to processed brownies, sourdough peanut butter brownies can be a more mindful option when enjoyed in moderation.