Grease a springform pan (26 cm Ø). Cream 125 g butter, sugar, vanilla sugar and 1 pinch of salt with the whisks of the mixer. Stir in the eggs one after the other. Mix flour, baking powder and nuts, alternating with the milk. Fill the dough into the form, smooth it down.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Wash nectarines, rub dry. Cut each nectarine into 8 columns. Place the nectarines in a fan-shaped circle on the dough. Press down lightly. Bake in a hot oven for about 40 minutes. Pass the jam through a fine sieve into a small pot. Warm up at low heat. After about 30 minutes baking time, spread the nectarines with it.
Take the cake out of the oven and let it rest on a cake rack for about 20 minutes. Loosen the edge of the springform pan. Let the cake cool down.
Select raspberries, wash if necessary. Dust the cake with icing sugar and spread the berries on top. Serve with whipped sour cream.