Grind the walnuts and chestnuts. Mix with biscuit crumbs and sugar. Add the butter. Put the mixture in a mold with a diameter of 22 cm (24 is also possible) and press it flat to create a bottom.
Beat the eggs until thick and creamy. Add the sugar, vanilla sugar and half of the dulce de leche. Add the cream cheese, quark and crème fraiche with pudding powder and milk to the egg mixture. Put the mixture on the prepared base and bake in a hot oven at 160 degrees for 50 - 55 minutes. Let cool down slowly with the door open. When the cake has cooled down, spread the rest of the Dulce de Leche over it and place in the fridge for at least 6 hours.
Tip:
If you want, you can replace the quark with cream cheese and the crème fraiche with sour cream.
Dulce de leche is a jam made from sweetened condensed milk.