Prepare the Graham Cracker Crust

Make the Crust: In a medium bowl, mix together the graham cracker crumbs, granulated sugar, and melted butter until the crumbs are evenly coated. Press the mixture firmly into the bottom of a 9x13-inch baking dish to form an even layer.

Chill the Crust: Place the dish in the freezer for about 10 minutes to allow the crust to set.

Make the Chocolate Layer

Melt the Chocolate: In a microwave-safe bowl, combine the chocolate chips and heavy cream. Microwave in 30-second intervals, stirring between each interval, until the chocolate is fully melted and smooth.

Layer the Chocolate: Pour the melted chocolate over the chilled graham cracker crust, spreading it out evenly with a spatula. Place the dish back in the freezer for about 10 minutes, or until the chocolate layer is set.

Make the Marshmallow Layer

Cream Cheese Mixture: In a large mixing bowl, beat the softened cream cheese until smooth. Add the marshmallow fluff and vanilla extract, and continue to beat until fully combined and creamy.

Fold in Whipped Topping: Gently fold in the thawed whipped topping until the mixture is light and fluffy.

Layer the Marshmallow Mixture: Spread the marshmallow mixture evenly over the set chocolate layer. Smooth the top with a spatula.

Freeze and Serve

Freeze: Cover the dish with plastic wrap or aluminum foil and freeze for at least 4 hours, or until the layers are firm.

Serve: Once frozen, remove the dish from the freezer and let it sit at room temperature for a few minutes to soften slightly for easier cutting. Slice into squares and garnish with additional graham cracker crumbs or mini marshmallows if desired.

Store: Store any leftovers in an airtight container in the freezer.