How to make
Mix the milk, egg yolks and sugar very well. To them add the flour, grated rusks, lemon zest, baking powder, rum and the egg whites that have been beaten to hard snow.
Pour the mixture into a buttered and floured form and bake in a preheated moderate oven.
After it cools, cut the layer into several smaller layers, smear them with cream. Smear the top of the cake with cream and put it in the fridge.
Making the cream: Boil the flour, egg yolks, rum and coffee to a thick cream and when it cools, add the butter. Beat and mix carefully with the whites that have been beaten to snow.