Put flour, icing sugar, vanillin sugar, orange peel and salt in a bowl. Add egg yolk and fat in small flakes. Work well with the dough hooks of the hand mixer. With cool hands quickly knead to a smooth dough.
Cover and refrigerate for 1/2 hour. Roll out the dough 2 mm thin on a lightly floured work surface. Cut out circles (5 cm Ø). Cut another circle (2.5 cm Ø) from the middle of the circles.
Place the resulting dough rings on a baking tray lined with baking paper. Knead the dough remains together and process as described above. Bake in a preheated oven (electric oven: 200 °C/ gas: level 3) for 7-10 minutes until golden brown.
Let the cookies cool down on a cake rack. To decorate, roast hazelnuts in a dry pan until brown. Put them in a sieve and rub off the brown skin. Coarsely chop the hazelnuts. Cream the fat, nougat and orange peel with the whisk of the hand mixer.
Pour into a piping bag with a perforated spout and spray in a circle onto the short pastry rings. Sprinkle with hazelnuts and press on a little. Place the cookies in the freezer for 15 minutes. Melt the chocolate coating in a hot water bath.
Dip the rings briefly into the chocolate coating, drain them a little and let them dry on a cake rack. Results in about 50 pieces.