For the apple-raisin muffins, preheat the oven to 180 °C. Cream butter, sugar, eggs. Mix baking powder with flour and cinnamon and stir in.
Cut apples into small pieces, sprinkle with lemon juice and fold into butter-sugar-egg mixture with hazelnuts and raisins. Pour the mixture into the muffin tray and bake for a quarter of an hour (test with a stick).