Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Line two trays with baking paper. Finely chop the nuts. Mix with flour, baking powder and oat flakes.
Cream butter, sugar, vanilla sugar and 1 pinch of salt with the whisks of the mixer. Stir in the eggs one by one and add the flour mixture by the spoonful.
Using two tablespoons of the dough, spread approx. 20 flat spots (5-6 cm Ø) from the dough onto the trays at a slight distance (flow slightly apart!). Bake one after the other in a hot oven for about 15 minutes. Remove from the oven and let it cool down.
Chop the couverture and melt in a hot water bath. Dip the cookies halfway into the chocolate coating, drain briefly and then allow to dry.