Prepare and bake cake in a 9x13" pan, according to box instructions. Allow cake to completely cool, then cut it into 1" cubes.Crumble half of the cake in your trifle dish or large bowl.
Sprinkle 2-3 tablespoons of Kahlua over the cake cubes.Combine 2 chocolate pudding boxes (3 oz. each) with 3 cups of milk and 1 cup of Kahlua. Spread half of the pudding on top of the cake crumbles.
Layer half of the whipped cream on top of the pudding. Sprinkle with half of the Heath bars and chocolate chips, if desired.Repeat layers, with Heath crumbles on top. Refrigerate at least 1 hour, serve and enjoy!