Preparing dough crumbs: use your hands to mix flour, sugar, cocoa, vanilla sugar, butter, and sour cream until you have crumbs.
Put some crumbs on the side for later. Pour the rest into a baking tin (spread it with parchment paper) and press, so that there is only one layer. Bake at 180 C for about 15 minutes.
Preparing the stuffing: use a blender to whisk the curd, milk, and the eggs.
Pour this mass on the baked foundation and put it in the oven for another 5-7 minutes. Take it out and pour the rest of the crumbs, mixed with walnuts. Again, put it in the oven and bake for another 30 minutes.
Once finished, take it out and wait for the pie to cool off. Then, put it in a fridge for a couple of hours. It tastes the best when cold. Enjoy!