Pie with prunes and hazelnuts

Dough: butter - 80 g; sour cream - 1 tbsp. the spoon; sugar - 1 tbsp. the spoon; yolk of 1 egg; ½ teaspoon of baking powder; a pinch of salt; flour ~ 200-225 g
Filling: butter - 100 g; flour - 100 g; chopped hazelnuts - 80 g; baking powder - 1 tsp; sugar - 75-100 g; a bag of vanilla sugar; egg - 2 pcs + the protein of one egg; cognac or rum - 1 tbsp. the spoon; cocoa powder - 1 tbsp. spoon (no slide); prunes (b / c) - 200 g
Preparation:
For the dough, beat the butter and sugar until fluffy. Add yolk, sour cream, mix. Mix the flour with baking powder and salt and gradually add to the dough - it should become soft and plastic, but should not stick to your hands. Put the dough in a baking dish, forming the sides. Put the form in the refrigerator for at least half an hour.
Pour the prunes with cognac or rum, leave for a couple of hours.
For the filling, beat soft butter with sugar and vanilla, add eggs and protein one by one.
Sift flour with baking powder and cocoa, combine with chopped hazelnuts.
Pour the nut mixture into the butter mixture, beat gently.
Put the filling on a chilled sand base. Spread the prunes on top, slightly melting the berries. Lay out the walnut-oil mixture, smooth out.
Bake the cake in an oven preheated to 180 C for about 40 minutes.