# What You'll Need:
→ Chocolate & Cocoa
01 - 3.5 oz bittersweet chocolate (60–70% cacao), chopped
02 - 1.75 oz milk chocolate, chopped
03 - 1.75 oz white chocolate, chopped
04 - 1/4 cup unsweetened cocoa powder
→ Sourdough & Wet Ingredients
05 - 1/2 cup sourdough starter (100% hydration, unfed or discard)
06 - 1/2 cup unsalted butter, cubed
07 - 2 large eggs
08 - 1 tsp vanilla extract
09 - 2 tbsp strong brewed espresso or 1 tbsp instant espresso powder dissolved in 2 tbsp hot water
→ Dry Ingredients
10 - 3/4 cup granulated sugar
11 - 1/4 cup light brown sugar, packed
12 - 3/4 cup all-purpose flour
13 - 1/2 tsp fine sea salt
# How to Make It:
01 - Preheat oven to 350°F. Line an 8x8-inch baking pan with parchment paper, allowing overhang for easy removal.
02 - Combine bittersweet chocolate and butter in a heatproof bowl. Place over a saucepan of gently simmering water (double boiler method), stirring until smooth. Remove from heat and cool slightly.
03 - Whisk granulated sugar and brown sugar into the chocolate mixture until combined. Add eggs one at a time, whisking thoroughly after each addition. Stir in vanilla extract and espresso.
04 - Fold sourdough starter into the wet mixture until fully incorporated.
05 - Sift together flour, cocoa powder, and salt. Gently fold dry ingredients into the wet mixture until just combined, avoiding overmixing.
06 - Fold milk chocolate and white chocolate pieces into the batter.
07 - Pour batter into prepared pan and smooth the top surface evenly.
08 - Bake for 32–36 minutes, until the center is just set and a toothpick inserted in the middle comes out with moist crumbs.
09 - Cool completely in the pan before lifting out with parchment paper overhang. Slice into 12 equal squares.
