• Line an 8X8 square metal pan with cling wrap. Make sure to stick it to the bottom of the pan and leave overhang to create a sling. This will help you lift the finished cake out of the pan.
• Make the pastry cream
• In a 2-quart stainless steel saucier, whisk together sugar, cornstarch, salt, egg yolks, and the milk
• Place saucepan over medium heat and whisk constantly as the pastry cream begins to thicken. This should take about 8 minutes.
• While it is thick, continue to whisk until mixture starts to bubble. once bubble let the mixture cook for just one minute longer then remove from the heat
• Once off of the heat add in the chopped chocolate, the butter and the vanilla
• Mix with a nonstick spatula until chocolate is completely melted and the mixture is homogenous. If you would like a really smooth pastry cream, now is when you can strain the mixture over a sieve. If you see clumps in your mixture, you MUST do this step. If it is smooth you can skip. Place mixture in a heat proof bowl and let chill in the fridge until its completely cool. This may take about an hour.

Make the Whipped Cream

• In a large bowl, add sugar and heavy cream. Using a balloon whisk or an electric mixer, whip the cream until peaks are just forming. Set aside for assembly.
• Place a 2 quart saucepan with 2 inches of water in it over medium heat
• Let the water come to a simmer
• In the bowl of a standmixer, add sugar and egg whites
• Place the standmixer bowl with the sugar and egg whites over the saucepan with simmering water
• Using a nonstick spatula, mix constantly as this mixture cooks
• Keep mixing to ensure that the egg whites do not clump and the mixture is cooking evenly
• After about 4 minutes, the granules of sugar should have dissolved and the mixture – to test this, scrape the nonstick spatula around the bowl and lift up, bringing some of the mixture with the spatula. Using your ring finger and your thumb, swipe a small amount of the mixture from the spatula and rub it in between your fingers. It will feel smooth rather than grainy. A MUCH easier way is to take the temperature. It should register 160F on a candy thermometer.
• At this point, remove the mixture from the top of the saucepan and place bowl into the stand mixer. Fit the stand mixer with a whisk attachment and whisk until stiff peaks form in the marshmallow. On high to medium speed, this should take about 10 minutes.

Assembly

• Line the first layer of the pan (on top of the saran or cling wrap) with a layer of graham crackers. Feel free to break them into pieces to cover the bottom in one flat layer
• Next, add 1/2 of the pastry cream on top of the graham crackers and smooth out with an offset spatula
• Add 1/2 of the whipped cream and then another layer of graham crackers. Then add the other half of the pastry cream, another layer of graham crackers followed by the last bit of the whipped cream.
• The layers will be as follows: Graham, Pastry Cream, Whipped Cream, Pastry Cream, Graham Cracker, Whipped Cream
• Smooth out the top of the icebox cake and top with all of the marshmallow topping
• Using a spoon, add some swoops and texture to the marshmallow and place entire pan into the freezer and let set in the freezer for at least 4 hours
• Remove from freezer and cut into slices
• Using a kitchen torch, torch the marshmallow meringue topping!