Ganache, the cream and chocolate mixture, is ready to use when it mounds slightly when dropped from a spoon. It will become firmer the longer it cools.
Glaze the cake on a rack with waxed paper under the rack; any extra drips of the ganache will fall onto the waxed paper. When the ganache hardens, you can easily and neatly transfer the cake to your serving plate.
Stir 2 tablespoons freeze-dried or powdered instant coffee (dry) or 1 tablespoon grated orange peel into the cake batter.