Milk: Take one cup of milk from the prepared 1 l and put it aside. Warm the remaining milk on the stove until it reaches 80C. It is crucial that the milk is not boiling while you're cooking the nockerl in it. When it is streaming inside the pot and about to boil, you are ready to go.
Meringue: While the milk is getting warm, separate the egg-whites and egg-yolks and beat the egg-whites until soft peaks form. Add the sugar and beat until stiff peaks form.
Nockerl: Take a spoonful of beaten egg-whites "snow" and use a second spoon to form a "nockerl" with it. Drop the nockerl into hot milk and let it cook for 3min. Flip it over and cook for another 3min. Take the nockerl out of the milk and put them in a sieve over a bowl to drain. Repeat until you've used up all the egg-whites. Carefully drain the remaining milk back into the large pot.
Custard: Mix the egg-yolks with few drops of vanilla essence and sugar, beating until frothy and pale yellow. Add flour and the one cup of milk you reserved at the beginning, constantly beating with a mixer. Pour the mixture back into the pot with hot milk and cook at medium heat until the cream thickens (it should reach 90 degree C). This will take some 15-20 minutes. Do not boil.
Cool: In a glass, layer the minced biscuits, then nockerl over it. Pour the hot vanilla cream over the nockerl, sprinkle with cocoa/chocolate and let it cool to room temperature. Cover with plastic foil and refrigerate for a few hours or until completely chilled.