It's like a punch in the mouth from a chocolate fist.
The recipe is more complicated than brownies out of a box, so read it through from start to finish once before you begin. Basically, we're going to make a chocolate base that gets used in both the brownie batter and the chocolate frosting. Then, we're going to make an icing base that gets used in both the chocolate frosting and the greeble frosting.
Note: if your chocolate base is still warm, make sure to add it to the batter in very small increments to avoid cooking the eggs.
Pour the batter in to a greased 8 inch by 8 inch pan and bake at 350°F for about 30 minutes (until a toothpick comes out clean). In the meantime, prepare the frostings...
In a separate bowl, combine about three quarters of the Frosting Base and the remaining Chocolate Base. Add powdered sugar until it is spreadably thick.
Use the remaining Frosting Base and about 1/4 cup of Kahlua to make a somewhat thinner, lighter colored frosting. Add powdered sugar until it is thick enough to hold itself into neat little lines. Put this in a pastry bag and attach a thin tip, such as the type you might use for writing or drawing greebles.
When the brownies are finished baking, cool them completely. Then spread on the chocolate frosting. Then, pipe on the greeble frosting in a randomish pattern that looks cool but doesn't really do anything. At your option, you may substitute lines, letters, or other decoration for greebles.