Spoon 4 cups of the ice cream over cooled crust, spreading evenly. Spoon 1/3 cup of the hot fudge topping into small microwavable bowl; cover and refrigerate. Microwave remaining topping in uncovered jar on High 1 minute or until softened. Stir topping; spoon and spread over ice cream in crust. Spoon and spread remaining 4 cups ice cream over topping. Freeze until firm, 4 hours or overnight.