Melt the butter in the microwave and let cool down a little.
Mix the oatmeal with sugar, vanilla sugar, flour, baking powder and coconut flakes in a bowl. Then stir in the melted butter, the egg and 3-5 tablespoons of mineral water with the hand mixer.
Place small portions of the dough with a teaspoon on a baking sheet lined with baking paper, leave about 5 cm space in between, and bake the biscuits in a preheated oven at 175 degrees for 15-20 minutes until golden brown.