Start to finish: 5 minutes
1¼ cups chilled double-strength coffee
1½ ounces chocolate liqueur
2 teaspoons sugar
Combine the coffee and chocolate liqueur in a tall glass. Add the sugar and stir for a minute or so, or until it dissolves. Sugar dissolves more slowly in chilled coffee than hot.
Top the glass with whipped cream, then drizzle chocolate sauce over it.