Preheat the oven to 350 degrees F (175 degrees C). Grease and flour a 9x13-inch dish.

Mix cake batter according to package directions, adding water, eggs, and oil as directed. Spread batter into the prepared dish.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 30 minutes. Cool and crumble.

Make pudding according to package directions, adding milk as directed.

Place 1/2 of the crumbled cake into a large trifle or other glass serving bowl. Pour 1/2 of the coffee over cake and spread 1/2 of the pudding on top. Cover with 1/2 of the whipped topping and sprinkle with 1/2 of the crushed candy bars. Repeat layers in the same order. Refrigerate until serving.