Sourdough Brownies Peanut Swirl (Printable)

Fudgy chocolate brownies made moist with sourdough discard and topped with creamy peanut butter swirl.

# What You’ll 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 - In a microwave-safe bowl, melt butter and chocolate together in 30-second bursts, stirring between each interval until completely smooth. Allow to cool for 3 minutes.
03 - In a large mixing bowl, whisk together sourdough discard, granulated sugar, eggs, and vanilla extract until thoroughly combined.
04 - Pour the cooled melted chocolate mixture into the wet ingredient bowl and whisk until the batter achieves a smooth consistency.
05 - Sift flour, cocoa powder, and salt into the chocolate batter. Fold gently with a spatula until just combined, taking care not to overmix.
06 - Pour the brownie batter into the prepared pan and smooth the top surface with a spatula.
07 - In a small bowl, stir peanut butter with powdered sugar if using until smooth. Drop spoonfuls of the peanut butter mixture over the brownie batter. Using a skewer or knife, gently swirl the peanut butter into the batter in decorative patterns.
08 - Bake for 28-32 minutes, until the center is just set and a toothpick inserted into the center emerges with moist crumbs.
09 - Allow brownies to cool completely in the pan before cutting into squares for serving.

# Expert Advice:

01 -
  • Puts sourdough discard to delicious use instead of throwing it away
  • Incredibly fudgy and moist texture that stays soft for days
  • The peanut butter swirl adds a beautiful marbled effect and complementary flavor
  • Simple ingredients you likely already have in your pantry
  • Ready in just 45 minutes from start to finish
  • Perfect for both experienced bakers and beginners
02 -
  • Use unfed sourdough discard for best results—the tang is subtle and enhances the chocolate
  • Don't skip the cooling step in the chocolate mixture; this prevents the eggs from cooking when combined
  • For the most dramatic swirl, drop the peanut butter in dollops rather than spreading it, then use a knife to create figure-eight patterns
  • Store brownies in an airtight container at room temperature for up to 4 days, or refrigerate for up to a week
  • These brownies freeze beautifully—wrap individually and freeze for up to 3 months
  • A toothpick test should yield moist crumbs, not wet batter or completely clean; this ensures fudgy texture
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