Apple wash, quarter, core and cut into cubes. Drizzle apple cubes with lemon juice. Mix flour, baking powder, 90 g oat flakes, 20 g raisins, sugar, salt and spices in a large bowl. Whisk sour cream, eggs and oil and stir into the flour mixture with a wooden spoon, not stirring for too long. Drain the apple cubes and fold 2/3 into the dough.
Line a muffin tin (12 troughs of 7 cm Ø each) with paper cups and spread the dough inside. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 25 minutes. Mix 10 g oat flakes, 20 g raisins and remaining apple cubes. After 15 minutes baking time, spread the mixture on the muffins and continue baking. Take out and let cool down