Pumpkin Better Than Anything Cake

1 box yellow cake mix
1 small can pumpkin puree (make sure it's not pumpkin pie filling)
1 - 14 oz. can sweetened condensed milk
1 - 8 oz. tub cool whip
1/2 bag Heath Bits
Caramel Sundae Sauce

Mix together the cake mix and the pumpkin puree (DO NOT add the other ingredients on the cake mix box).  Pour batter into a well greased 9x13 baking dish.  Bake at 350* according to the directions for a 9x13 cake on the cake mix box.  Let cool for about 10 minutes after baking.  Using the bottom of a wooden spoon, poke holes all over the top of the cake.  Pour the sweetened condensed milk over the cake, filling the holes.  Refrigerate for 30 minutes.  Spread the cool whip over top of cake.  Sprinkle on the Heath bits, and drizzle caramel over top (just to your liking).  Refrigerate for 3-4 hours, or overnight (best).