Pour a 14 oz. can of sweetened condensed milk into a 2-cup glass measuring cup, and cover the top with aluminum foil. Place the covered measuring cup in a 3 1/2-quart crock pot. Carefully pout hot water into the crock pot to reach the level of the condensed milk in the measuring cup. Cover the crock pot with its lid, and cook on LOW for 9 hours. Carefully remove the measuring cup from the crock pot, and let the caramelized milk cool completely. (You may speed this up by placing it in the refrigerator after it has cooled a bit initially.) Spread the caramelized milk on the bottom of the graham cracker crust. Spoon whipped topping over the top, and spread it in an attractive manner. Sprinkle with Heath bar toffee candy crumbles. Cover with plastic wrap and chill for at least 2 hours before serving. This is yummmmmy!!!