01 -
Preheat oven to 350°F (175°C). Grease a 7 X 11-inch baking pan or line it with parchment paper for easy removal.
02 -
In a large bowl, whisk together melted butter, granulated sugar, and brown sugar until smooth and combined. Add eggs one at a time, whisking well after each addition. Stir in vanilla extract and sourdough starter discard. The mixture may appear slightly lumpy, which is normal.
03 -
In another bowl, sift together all-purpose flour, cocoa powder, salt, and baking powder. Ensure the dry ingredients are evenly distributed.
04 -
Gradually add the dry ingredients to the wet mixture, stirring until just combined. Avoid overmixing. Fold in the chocolate chips.
05 -
For a long fermentation process, cover the bowl with plastic wrap and refrigerate the batter for 12-24 hours before baking. This step is optional.
06 -
Pour the brownie batter into the prepared pan, spreading it evenly. Bake for 25-30 minutes or until a toothpick inserted into the center comes out with a few moist crumbs, keeping the center slightly soft. The brownies will firm up as they cool.
07 -
Allow the brownies to cool completely on a wire rack before cutting. For cleaner cuts, refrigerate for 30 minutes after cooling. Optionally, dust with powdered sugar or drizzle with melted chocolate before serving.