Preheat the oven to 350 F degrees. Prepare an 8×8 inch pan grease it or just cover it with baking paper ad set it aside. Put the butter and the chocolate in the bowl to melt in microwave oven. It doesn’t have to melt completely, take it out after a minute and stir until it becomes nice, melted and smooth. Add sugar, vanilla, coffee (granulated and liquid), flour and salt. Stir it well and add the eggs last. Pour the batter into the prepared pan and bake it for about 20 to 25 minutes. Check if it is baked with the toothpick …it has to come out clean. Leave the cake to cool until you make the frosting. Put the butter, milk and the cocoa powder into the saucepan and heat it. Whisk it until it boils and remove it from the heat. Add the vanilla and the confectioners sugar. As it cools the frosting is getting harder. Spread the frosting evenly over the cake and refrigerate for a few hours.
Notes
Cut with a warm knife, because the cold knife sticks to the frosting.