Peel and quarter apples, remove core. Dice apple quarters, sprinkle with lemon juice. Chop the nuts.
Cream fat, 200 g sugar, salt and vanilla sugar with the whisk of the hand mixer. Stir in the eggs one after the other. Mix flour and baking powder and stir into the fat-egg mixture. Fold in apples and nuts.
Pour into a greased, flour-dusted ring cake mould (26 cm Ø, approx. 2 litres capacity). Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 45 minutes.
Remove from the oven, turn over and allow to cool on a cake rack.
Sort blackberries. Simmer remaining sugar with 120 ml water for about 5 minutes. Puree the blackberries with sugar syrup in a tall container. Cut the ring cake into pieces and serve with blackberry sauce.