Sourdough Cosmic Chocolate Brownies (Printable)
Fudgy, tangy chocolate brownies made with sourdough starter and topped with chocolate chips and rainbow sprinkles.
# What You'll Need:
→ Wet Ingredients
01 - 1/2 cup unsalted butter, melted
02 - 7 oz dark chocolate (70% cacao), finely chopped
03 - 3/4 cup granulated sugar
04 - 1/4 cup packed light brown sugar
05 - 2 large eggs, room temperature
06 - 1 teaspoon pure vanilla extract
07 - 1/2 cup active sourdough starter (100% hydration, unfed or discard)
→ Dry Ingredients
08 - 2/3 cup all-purpose flour
09 - 1/4 cup unsweetened cocoa powder
10 - 1/2 teaspoon fine sea salt
→ Cosmic Topping
11 - 3.5 oz mini chocolate chips or candy-coated chocolate pieces
12 - 3 tablespoons rainbow sprinkles
# How To Make:
01 - Preheat the oven to 350°F. Line an 8×8-inch baking pan with parchment paper, leaving an overhang on two sides for easy removal.
02 - Combine the butter and dark chocolate in a heatproof bowl set over simmering water or microwave in 30-second intervals, stirring between each, until completely smooth. Allow to cool slightly for about 5 minutes.
03 - Whisk the granulated sugar and brown sugar into the melted chocolate mixture until glossy and well blended. Add the eggs one at a time, whisking thoroughly after each addition. Stir in the vanilla extract.
04 - Gently fold the sourdough starter into the batter using a spatula until fully incorporated and no streaks remain.
05 - Sift the flour, cocoa powder, and salt together into a separate bowl. Gradually fold the dry mixture into the wet batter until just combined. Be careful not to overmix to keep the brownies tender.
06 - Pour the batter into the prepared baking pan and spread it into an even layer. Scatter the mini chocolate chips or candy-coated pieces evenly across the surface, then generously sprinkle with rainbow sprinkles.
07 - Bake on the center rack for 28 to 32 minutes, or until a toothpick inserted into the center comes out with moist crumbs clinging to it. Avoid overbaking for the fudgiest texture.
08 - Transfer the pan to a wire rack and let the brownies cool completely in the pan. Use the parchment overhang to lift them out, then cut into 16 even squares.
# Expert Tips:
01 -
- The sourdough starter adds a mellow tang that cuts through the richness and keeps you reaching for another square.
- That rainbow sprinkle topping makes these impossible to ignore on any dessert table.
02 -
- Underbaking slightly is the key to that dense fudgy center, so set your timer closer to 28 minutes and trust the residual heat.
- Overmixing after adding the flour will build gluten and give you a spongy texture instead of the dense chew you want.
03 -
- Use parchment overhangs to lift the entire slab out of the pan before cutting, so you never scratch the bottom serving brownies with a knife inside the pan.
- A sprinkle of flaky sea salt on top right before baking adds a sophisticated edge that balances the cosmic sweetness beautifully.