In a bowl, combine graham cracker crumbs and melted butter. Press mixture evenly into the bottom of a 9x13 inch baking dish.
In a separate bowl, whisk together instant vanilla pudding mix and milk until smooth and thickened. Spread evenly over the graham cracker crust.
In a small saucepan over low heat, melt semi-sweet chocolate chips with heavy cream, stirring until smooth. Pour over the pudding layer.
In a medium bowl, beat softened cream cheese and powdered sugar until smooth. Gently fold in the whipped topping until well combined. Spread evenly over the chocolate layer.
Chill in the refrigerator for at least 4 hours, or until firm.
Cut into squares and serve cold.
Notes
For a firmer crust, you can bake the graham cracker mixture for 8-10 minutes at 350°F (175°C) before proceeding. This cake is best served within 2-3 days.