Carmel Pie

1 can sweetened condensed milk
1 Graham Cracker Crust
1 tub Cool Whip

put unopened can of sweetened condensed milk in a pan that is filled with enough water to cover can completely. Let boil for 4 hours on high. It is very important to watch this and not let the water evaporate below the top of the can. After the 4 hours remove from water and let stand for 5 minutes. Open can carefully and pour into graham cracker crust. Let cool in refrigerator and then top with Cool Whip.