2/3 cup whole milk
1 cup heavy cream
1/2 cup granulated sugar
4 large egg yolks
2 tbsp cornstarch
6 1/2 oz Nutella (by weight)
2 tbsp Frangelico
a box of graham crackers
Line a 9" square cake pan with plastic wrap. Set aside.
Scald the milk, cream, and 1/4 cup of sugar in a small saucepan.
In the mean time, whisk together egg yolks, 1/4 cup of sugar, and cornstarch in a large mixing bowl until smooth. Temper the eggs by pouring in a bit of the hot milk into the egg mixture while whisking. Keep adding milk to eggs and continue whisking until incorporated. Pour mixture back to saucepan.
Cook over medium high heat and stir constantly with a silicone spatula or wooden spoon. When it starts to boil, the custard will thicken considerably. Keep stirring vigorously for another 15 seconds. Remove from heat.
Empty the cooked custard into a large mixing bowl. Whisk in Nutella and Frangelico until smooth
To assemble icebox cake, line cake pan with a layer of graham cracker and top with 1/2 cup of pudding. Smooth pudding evenly using an offset spatula. Repeat with another layer of graham cracker and pudding three more times until you have 8 layers in total. The top layer should be Nutella pudding. Level with offset spatula.
Wrap the pan with plastic wrap and chill in the fridge for 24 hours. During this time, the moisture from the pudding will soften the graham crackers until they take on a cakey texture. Don’t rush it! If you want very clean neat cuts, I would put it in the freezer for 3 hours until solid.
To serve the cake, lift it out of the cake pan with the help of plastic wrap. Peel off the plastic wrap and transfer cake to serving plate. Cut with a knife dipped in hot water and divide into 9-12 pieces. If the cake had been frozen, let it stand at room temperature for about 30 minutes before serving.