Melt the butter. Stir in the oat flakes and let it cool down. In the meantime beat eggs, sugar, salt and vanilla sugar for at least 10 minutes until frothy. Mix flour and baking powder, stir in.
Stir everything into the fat-oatmeal mixture. Using 2 teaspoons, place small heaps on three baking trays lined with baking paper. Bake the trays one after the other in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 20 minutes.
Let it cool down on a grid.