Preheat oven to 350°F.
In a large bowl, mix together butter and sugar until well combined. Add eggs, vanilla and coffee and stir until well blended and smooth.
In a medium bowl, combine flour, cocoa, baking powder and salt. Add to the egg mixture and stir by hand just until combined.
Spoon the batter mini muffin cups that have been sprayed with non-stick spray. Bake for 12-15 minutes, until puffed but still soft to the touch. Do not overbake! Cool in the pan on a wire rack.
Makes 24 brownies.