Chocolate heath cake

1 pk chocolate cake mix
     14 oz Sweetened condensed milk
      6 oz Heath Bits 'O Brickle
      4    Heath Candy bars (freeze)
      8 oz Cool Whip
 
  Bake cake as directed on box. As soon as cake comes
  out of the oven, punch holes in the top of the cake
  with a straw. Spread condensed milk on top. Sprinkle
  package of brickle chips on top of cake. Cool cake.
  Spread cool whip on top. Mash frozen Heath Bars (use a
  hammer) and spread on top of cake. Keep refrigerated.