Step 1

Preheat the oven to 350°F. Lightly grease a 9" x 13" pan. Line with parchment paper, optional.

Step 2

In a saucepan, melt the butter over medium heat. Stir in the sugar and cook until mixture is hot (about 110°F to 120°F), but not bubbling.

Step 3

In a large mixing bowl, whisk eggs, cocoa, salt, baking powder, espresso powder, and vanilla until smooth. Add the hot butter/sugar mixture and stir until smooth. Add the flour and stir until smooth.

Step 4

Let the batter cool in the bowl for 20 minutes then stir in the chips. Spread batter into prepared pan.

Step 5

Bake for about 30 minutes, until the brownie edges are set and a cake tester inserted into the center comes out with just a few moist crumbs clinging to it. Remove them from oven and cool completely on a rack before cutting.