Preheat the oven to 350
Grease the baking pan with butter on all sides
Chop the chocolate, and combine it with 1/4 cup cocoa powder and the espresso powder/coffee grounds
Melt the butter in the saucepan at medium heat
Pour the butter over the chocolate mixture. Let it sit for 2 minutes, and then whisk until smooth
Combine the white and brown sugar, salt, vanilla, and eggs in a mixing bowl. Use the electric mixer to beat it all together until it is light and fluffy, about 10 minutes
Pour in the chocolate mixture and mix completely
Add in the remaining 1/2 cup cocoa powder and the all-purpose flour and fold into the batter with the rubber spatula
Pour the finished batter into the baking pan. Smooth the top with the spatula
Bake for 40 minutes, and then stick a knife or toothpick in the center to see if it comes out clean. If it does, the brownies are done
Let the brownies cool for at least 20 minutes