Wash the blueberries, sort them and then let them drain.
Melt the fat and then let it cool down a little.
Mix the flour with baking powder, salt, vanilla sugar and 100 g sugar. Whisk the buttermilk with the eggs and slowly pour into the flour-sugar mixture. Mix everything with the whisk of the hand mixer to a smooth dough. Finally stir in the melted butter.
Grease a 30 cm pie form, pour in the dough, smooth out. Spread the blueberries on top, sprinkle with the remaining sugar (100 g).
Bake in a preheated oven (200 degrees) for about 30 minutes until it is nicely browned. Let cool down.