Preheat the over to 325 F. Butter an 8″ square baking dish.
Combine the flour and baking powder then set aside.
Melt the chocolate, cocoa powder, espresso powder, and butter together in a metal bowl over a pot of simmering water. Stir until completely smooth and reserve for later.
In a stand mixer fitted with the whip attachment, combine the sugar, eggs, and salt. Whip for 5 minutes at high speed until barely yellow. Reduce to low speed and slowly add the chocolate mixture.
Stop the mixer and add in the flour that was set aside. Gently mix by hand until just combined.
Pour batter into the prepared pan and bake for 20 minutes* until just set and the sides are pulling slightly away from the pan.
Cool brownies in the pan on a rack. Remove from pan and cut. For mixing into gelato or ice-cream chunks that are roughly 1-inch cubes work well.