• Line an 8 1/2 x 4 1/2-inch or 9 x 5-inch loaf pan (or a square baking pan) with parchment paper, leaving an overhang on the sides to lift the cake out. This makes slicing and serving easy! Set aside.

Make the Ganache

• Place chopped chocolate in a bowl. Heat the heavy cream in a small saucepan until it begins to gently simmer. Pour over the chocolate and let sit for 2-3 minutes. Slowly stir together until combined and the chocolate has melted. Cover and refrigerate until set and spreadable while preparing the cake.

Make the Marshmallow Cream Filling

• In a large bowl, combine the whipped topping and marshmallow fluff.

Layer the Cake

• Spread a thin layer on the bottom of the prepared pan. This helps anchor the crackers. Top with a single layer of graham crackers. You will need to break them apart in some places to arrange them evenly. Spread 1/4 of the marshmallow cream evenly over the crackers. Add a layer of graham crackers over the cream and top the crackers with half of the chocolate ganache. Repeat this layer 2-3 more times (or until the pan is filled) and end with the final layer of marshmallow cream.
• Cover and refrigerate for at least 12 hours or overnight. You can also freeze the ice box cake for about 1 ½ hours, allowing the graham crackers to be more crisp and easily sliced when serving.
• Before serving, garnish with additional graham cracker crumbs, chocolate chunks and mini marshmallows, if desired.