First separate an egg. Chill the egg whites for the quark cream.

Knead 125 g flour, 30 g sugar, the cold butter pieces, 1 egg yolk and 1 tablespoon cold water to form a smooth dough.

Grease the bottom of the springform pan. Roll out the dough on a floured surface into a circle about 25 cm in diameter. Place the dough on the springform pan, adjust the size. Prick the dough several times with a fork and refrigerate for 15 minutes.

Preheat the oven to 175 ° C O / U heat.

Bake the dough in a hot oven for 15-20 minutes and allow to cool.

Roast the desiccated coconut in a pan without fat until golden brown, put in a bowl and let cool. Sort the blueberries, wash and drain. Grease the edge of the springform pan, dust a little with flour and place around the base of the springform pan.

Sprinkle the pre-baked and cooled shortcrust pastry base with the cooled coconut flakes and spread the blueberries on top.

Mix the flour with the cornstarch. Separate 2 eggs and add the egg whites to the 1 frozen egg white.

Mix the quark, 2 egg yolks, 3 whole eggs, 175 g sugar, vanilla sugar, flour and cornstarch mixture, grated lemon zest and lemon juice together well in a bowl.

Using a clean whisk, beat the 3 egg whites until stiff, sprinkling in 25 g of sugar.

Carefully fold the egg whites into the curd cream. Then pour the mixture into the springform pan over the blueberries and smooth out.

Bake the cake in a preheated oven at 175 ° C O / U heat, about 45 minutes. After baking, turn off the oven and let the cake rest in the oven with the door half open for a few more minutes. Take out, loosen the edge and let the cake cool in the tin on a wire rack. When the cake is completely cold, remove it from the mold and dust with powdered sugar.