1 Prepare chocolate cake according to package directions, and bake in a 9×13-inch pan. Cool. Cut into squares and pour coffee-flavored liqueur over cake. Prepare chocolate pudding according to package directions.
2 In large trifle bowl or other glass bowl, crumble half of cake. Top cake with half of chocolate pudding, half of crumbled candy bars, and one container of whipped topping. Repeat layering. Shave chocolate with a vegetable peeler for garnish. Keep refrigerated until serving.