Mix the sugar, vanilla sugar, egg yolk and lemon zest together well.
Whisk the custard powder with the milk and stir in together with the quark. Mix nuts and breadcrumbs and stir in as well. Beat the egg white until stiff and fold in with the currants.
Pour the mixture into a greased baking dish, sprinkle with the almond flakes and bake in the oven at 180 degrees for about 40-50 minutes.