Sourdough Discard Brownies Peanut Butter (Printable)

Fudgy, moist chocolate brownies featuring sourdough discard and creamy peanut butter swirl for rich flavor.

# What you need:

→ Chocolate & Butter

01 - 1/2 cup unsalted butter
02 - 1 cup semisweet chocolate chips or chopped chocolate

→ Wet Ingredients

03 - 1/2 cup sourdough discard, unfed
04 - 1 cup granulated sugar
05 - 2 large eggs
06 - 1 teaspoon vanilla extract

→ Dry Ingredients

07 - 1/2 cup all-purpose flour
08 - 1/4 cup unsweetened cocoa powder
09 - 1/2 teaspoon fine sea salt

→ Swirl

10 - 1/3 cup creamy peanut butter
11 - 1 tablespoon powdered sugar, optional

# How to make it:

01 - Preheat oven to 350°F. Line an 8x8 inch square baking pan with parchment paper.
02 - Combine butter and chocolate chips in a microwave-safe bowl. Melt in 30-second intervals, stirring between each burst until smooth. Cool for 3 minutes.
03 - Whisk together sourdough discard, granulated sugar, eggs, and vanilla extract in a large mixing bowl until fully incorporated.
04 - Pour the cooled melted chocolate into the wet ingredient mixture. Whisk until completely smooth.
05 - Sift flour, cocoa powder, and salt into the chocolate mixture. Gently fold with a spatula until just combined, avoiding overmixing.
06 - Pour batter into the prepared pan and smooth the surface evenly.
07 - Combine peanut butter and powdered sugar in a small bowl until smooth. Drop spoonfuls across the brownie batter. Use a skewer or knife to create swirl patterns throughout.
08 - Bake for 28-32 minutes until the center is just set. A toothpick inserted should come out with moist crumbs.
09 - Allow brownies to cool completely in the pan before cutting into 16 squares.

# Helpful Hints:

01 -
  • You get to feel resourceful using discard that normally gets tossed, plus the sourdough adds a subtle tang that deepens the chocolate flavor in ways you won't expect.
  • The peanut butter swirl looks impressive enough to serve guests but comes together in under 45 minutes, which means zero stress baking.
  • These brownies stay fudgy and moist for days, making them perfect for meal prep or last-minute desserts when you need comfort food fast.
02 -
  • Using unfed sourdough discard is essential; fed starter has different hydration and will throw off your brownie texture entirely—I learned this the hard way by pulling a gummy batch from the oven.
  • The peanut butter swirl separates beautifully during baking only if you use it at room temperature; cold peanut butter won't soften into the batter and just sits on top instead.
03 -
  • Use chocolate you actually enjoy eating because there's nowhere to hide in brownies—this single ingredient choice affects everything, so splurge on good quality.
  • Room temperature sourdough discard mixes more evenly than cold discard straight from the fridge, which can create lumps; pull it out 15 minutes before you bake.
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