Dissolve 1/4 cup instant coffee granules (I use decaf), 1/2 cup instant chocolate drink mix (like Nesquik) and 1/2 cup sugar in 1 1/2 quarts VERY HOT water. Cool the mixture in the fridge.
About 20 minutes before you're ready to serve, pour the cold coffee/chocolate mixture into a punch bowl. Add 1/2 gallon of vanilla ice cream and 1/2 gallon of chocolate ice cream (I add it in big scoops). It looks a bit ugly at first, but keep stirring it around until the ice cream starts to soften. . .and the consistency of the punch begins to look more like a milkshake. This usually takes about 15 minutes to get it looking right. When you serve, ladle it into punch cups and add some spray whipped cream to the top.