Mix all ingredients for the base well together and spread on a greased baking sheet. Bake at 180 ° C for 15 minutes. In the meantime, bring the milk to the boil and mix the custard powder and sugar according to the instructions. Let the solid pudding mixture cool for at least 15 minutes. Then fold in the sour cream and spread the mixture on the pre-baked base. Drain the peach wedges from the tin well and distribute them evenly on the pudding-sour cream mixture. Bake everything together again for 15 minutes at 180 ° C. Finally sprinkle with almonds, pistachios or hazelnuts and cover with a clear cake topping.