Put 300 g of frozen berries, lemon juice and 3 tbsp. sugar in a pot and simmer for about 5 minutes. Remove from the heat and let it cool down. Peel and quarter apples, cut out core. Cut quarter into slices
Cream butter, 175 g sugar, vanillin sugar and salt with the whisk of the hand mixer. Stir in the eggs one by one. Mix flour, hazelnuts and baking powder and stir in alternately with the milk
Put the dough on a greased fat pan of the oven (32 x 39 cm), smooth it down. Spread apples and 300 g frozen berries on top. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 45 minutes. Take out of the oven and let it cool down. Warm the jelly and brush the fruit lightly with it. Serve with berry sauce. Whipped cream tastes good with it
waiting time 3-4 hours