How to make
Brew the coffee in 1 cup water and leave it to settle. Beat the butter with 2 tablespoons powdered sugar to cream. On low heat, beat the 4 egg yolks with 1 cup sugar until the mixture thickens.
Remove the egg cream from the heat and set it aside to cool, then add it to the butter cream spoon by spoon. Finally, add half the coffee. Heat the milk with the remaining coffee. In a platter or tray, start to stack the cake, while dipping each biscuit in the milk with coffee briefly.
Make 3 layers, while putting buttered cream between each. Top the biscuit cake with the egg whites beaten with 2 teaspoons powdered sugar. Optionally, you can make a different kind of glaze.