For the crumbles, knead butter in pieces, 60 g sugar, 60 g flour, muesli and 1 pinch of salt with your hands to form crumbles. Place two paper baking cups in each of the twelve hollows of a muffin tray. Preheat the oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer).
Beat the eggs and 150 g sugar with the whisk of the mixer until thick and creamy. Stir in oil and sour cream briefly. Mix 200 g flour and baking powder, sieve over the egg mixture and stir in briefly. Fold in frozen raspberries.
Spread the dough into the moulds. Sprinkle with crumbles. Bake in a hot oven for 30-35 minutes. Let cool on a cake rack.
The muffins also taste great with a berry mix from the freezer. In summer you can of course also have fresh raspberries and red or black currants.