Sourdough Brownies Peanut Swirl (Print)

Fudgy chocolate brownies enriched with sourdough discard and swirled with creamy peanut butter.

# Components:

→ 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)

# Directions:

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 intervals, stirring until smooth. Allow to cool for 3 minutes.
03 - In a large mixing bowl, whisk together sourdough discard, sugar, eggs, and vanilla extract until well combined.
04 - Pour the cooled chocolate mixture into the wet ingredients bowl and whisk until smooth.
05 - Sift flour, cocoa powder, and salt into the chocolate mixture. Fold gently with a spatula until just combined, avoiding overmixing.
06 - Pour batter into the prepared pan and smooth the surface with a spatula.
07 - In a small bowl, combine peanut butter with powdered sugar if using until smooth. Drop spoonfuls over the brownie batter. Use a skewer or knife to swirl peanut butter throughout the batter in decorative patterns.
08 - Bake for 28 to 32 minutes until the center is just set and a toothpick inserted comes out with moist crumbs.
09 - Allow brownies to cool completely in the pan before slicing into 16 squares.

# Expert Advice:

01 -
  • You finally have a delicious reason to stop feeling guilty about that sourdough starter sitting in your fridge.
  • The discard makes these brownies almost irresponsibly moist without any weird texture or aftertaste.
  • That peanut butter swirl melts into warm brownie—it's the kind of detail that makes people think you spent way more time than you actually did.
02 -
  • The sourdough discard should be unfed and at room temperature—don't use a freshly activated starter or your brownie will taste sour instead of complex.
  • Baking time is genuinely a range because ovens vary wildly; start checking at 28 minutes and remember that slightly underbaked is infinitely better than overbaked with these.
03 -
  • Don't skip cooling the chocolate before mixing it with eggs—even 3 minutes makes the difference between silky and scrambled.
  • If your sourdough discard is particularly bubbly and active, use it at peak fermentation for maximum moisture, but unfed discard works just fine if that's what you have.
Back