Prepare the topping. Prepare the pack of vanilla pudding with the milk and sugar according to the instructions. Fold in the sour cream. Drain the mandarins in a colander.
For the dough, beat the margarine with the sugar until frothy, add the eggs, flour and baking powder and knead everything until a smooth dough is formed.
For the crumble, mix the sugar, butter and flour with a hand mixer with the dough hook to form a crumbly crumble dough.
Grease a baking sheet well and spread the dough as evenly as possible on the bottom of the sheet with a rolling pin or your hands. Spread the sour cream pudding evenly on top and then the drained mandarin pieces. Sprinkle everything with the sprinkles.
Bake the cake in a fan oven at 180 ° C (normal stove approx. 200 ° C) until the crumble is golden yellow (approx. 30 minutes).