1 cup (2 sticks) butter
2 1/4 cups sugar
4 large eggs
1 1/4 cups cocoa powder
1 teaspoon salt
1 teaspoon baking powder
1 teaspoon espresso powder, optional
1 tablespoon vanilla extract
1 1/2 cups all-purpose flour
2 cups semi-sweet chocolate chips
Pre-heat the oven to 350 degrees. Butter a 9×13 baking dish.
In small saucepan over low heat, melt butter completely. Stir in sugar and continue cooking for 1-2 minutes, stirring constantly. Do not allow sugar mixture to boil.
Pour butter mixture into a large bowl or stand mixer, beat in cocoa powder, eggs, salt, baking powder, espresso powder, and vanilla extract. Mix until well combined.
Stir in the flour and chocolate chips until well combined.
Spread into prepared pan (batter will be very thick and sticky) and bake for about 30 minutes, until a tester comes out mostly clean.
The edges should be set and the center should still look slightly moist, but not uncooked.
Cool on a wire rack.
H/t to Cass, via https://www.bunsinmyoven.com/2009/10/15/good-ol-homemade-brownies/