Mix cake mix with melted margarine and condensed milk, Spread out 1/2 of the mixture into a 9x13 pan. Bake at 350~ for 10 minutes. Slice candy bars into little slices. Lay these on top of the baked crust. With the remaining batter-crumble it on top of the candy bars. It will have a crumbly texture. No need to spread it on top to make it smooth. Put it back into the oven and bake it at 350~ for 20 min.