Beat sugar, eggs, butter and salt until thick and creamy. Mix the oat flakes, hazelnuts, muesli and baking powder together, add and stir well. Then fold the oatmeal into the batter.
Line a baking sheet with parchment paper and place small mounds of dough on it using 2 teaspoons.
Preheat the oven to 180 degrees. Bake the cookies on the middle rack for about 12 to 15 minutes until golden brown.