01 -
Set oven temperature to 350°F (177°C) and allow to fully preheat.
02 -
Line an 8 x 8 inch square pan with parchment paper and coat with non-stick spray. Set aside.
03 -
In a large bowl, combine eggs, melted butter, buttermilk or milk, packaged brownie mix, cocoa powder, and espresso powder. Blend using an electric mixer on low speed until just combined, approximately 1 minute.
04 -
Pour the prepared batter into the lined baking pan. Smooth the surface evenly with a spatula.
05 -
Bake in preheated oven for 37 to 40 minutes, or until a toothpick inserted into the center comes out clean.
06 -
Allow the brownies to cool completely. Using the parchment paper, lift from the pan, slice into portions, and serve.