01 -
Heat your oven to 350°F with the rack in the middle. Butter an 8-inch aluminum pan and line it with parchment paper. The aluminum pan is key for even baking.
02 -
Melt your butter in a medium saucepan over medium-low heat. Whisk in the sugar until it gets nice and shiny (about 2-3 minutes), then take it off the heat.
03 -
Whisk in eggs and yolks one at a time until smooth. Add cocoa, sourdough discard, vanilla, coffee if using, baking powder, and salt. Mix until well combined.
04 -
Fold in those chocolate chips until they're mostly melted, then gently fold in the flour just until everything comes together.
05 -
Pour your batter into the pan and spread it evenly. Bake for 60-75 minutes until a toothpick comes out clean. If the top starts getting too dark, cover loosely with foil.
06 -
Let the brownies cool in the pan for an hour, then move to a wire rack to finish cooling. Once completely cool, cut into 16 squares.