DO NOT OPEN THE CAN of sweetened condensed milk! Just remove the label and shake it up as well as you can. DO NOT OPEN THE CAN! Set it aside.
Get 2 large pots and fill both with water. Make sure one pot will hold enough water to cover the top of the can of sweetened condensed milk completely by at least 1 inch. Place the UNOPENED can of sweetened condensed milk in the pot of water that completely covers the can by at least 1 inch. Bring both pots of water to a complete boil. Keep the unopened can of sweetened condensed milk covered at all times with boiling water from the other pot of boiling water. Refill boiling water pot as often as needed. Boil the can of sweetened condensed milk for exactly 3 hours (yes! 3 whole hours!). Make sure to keep the top of the can covered at all times with boiling water! If you don't, the can will explode! When you have boiled the can of sweetened consdensed milk for 3 hours, turn off both pots of water and carefully remove can from the water. Set on a folded towel or pot holder to cool completely (at least 4 to 6 hours). DO NOT OPEN THE CAN UNTIL IT IS COMPLETELY COOL!!! Once the can has cooled, open can and using a spatula spread the caramel into the graham cracker crust. Spread the Cool-Whip on top of the caramel. Sprinkle with the topping of your choice (listed above). Put in freezer for at least 4 hours. Set out 10 to 15 minutes before serving. Store leftovers (if you have any!) in the freezer. The caramel is also great to spread between cake layers or on top of cupcakes too. Also great to heat up and drizzle over ice cream. You can boil several cans of unopened sweetened condensed milk at a time. Just make sure all cans of sweetened condensed milk stay covered at all times during the 3 hours the cans are boiling. Be sure to always have the other pot of boiling water to add to the pot as needed. Enjoy!