Whisk butter, egg yolks, 200 g sugar and vanilla sugar in a bowl with the whisk of the hand mixer until creamy. Mix flour, ground almonds and baking powder. Stir into the egg yolk mixture in portions until you have a smooth dough.
Grease a springform pan (26 cm Ø) and dust with flour. Put the dough into the form and smooth it down. Pre-bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 15 minutes.
Berries selected. Spread half the berries on the dough and bake for another 20-25 minutes.
Roast the flaked almonds in a pan without fat. Take out and mix with 2 tablespoons of sugar and let it cool down. Stir jam until smooth and mix with the remaining berries. Take the cake out of the oven and spread marinated berries on top.
Spread almond flakes on the cake and let them cool on a cake rack. Remove from the tin and let it cool completely.