For the apple oatmeal muffins, peel apples. Grate coarsely with a grater. Sprinkle with lemon juice. Mix yogurt, sugar, egg, oil, vanilla sugar and cinnamon.
Briefly mix in grated apples and oat flakes. Mix flour with baking powder and stir in. Bake at 180 degrees for approx. 30 – 40 minutes. (test with chopsticks)
Then let rest in the form for approx. 5 – 10 minutes.