For the blackberry tart, sort and clean the blackberries. If possible, do not wash them.
Preheat the oven to 200 °C.
Quickly knead the butter with the flour, yolks, sugar, vanilla sugar, baking powder and a pinch of salt into a dough.
Leave to rest in the refrigerator for half an hour.
Press the dough into a greased springform pan (Ø 26 cm) and pre-bake for about 10 minutes.
For the topping, beat the egg whites until stiff and add the powdered sugar by the spoonful.
Sprinkle the almonds on the pre-baked dough, spread the blackberries on top and brush the beaten egg whites on top.
Bake the blackberry tart for about half an hour.