1. Cut the cake layer into 2-bite rounds using a 1 ½-inch round cookie cutter (straight-sided) and place these on a cooling rack resting over a parchment-lined baking tray, and so there is a 2-inch gap between them.
2. Heat the chocolate glaze until it is just melted (about 120 F) and spoon the glaze over each petite four so that the top and sides are completely covered. Chill these for about 20 minutes, then pour a second layer of glaze over them. Decorate the tops of the Petit Fours as you wish, with dragees, coloured sugar, gold dust or candied fruit. Chill the Petit Fours and then lift them onto your serving plate.
3. The petit fours can be stored, refrigerated, for up to 3 days.