Warm 100 ml of milk in a pot lukewarm. Sieve 500 g flour into a large mixing bowl. Add vanilla sugar and 1 pinch of salt. Crumble the yeast and mix with sugar until the yeast dissolves and becomes liquid.
Add yeast, lukewarm milk and 3 eggs to the flour in the bowl and knead with the dough hooks of the mixer for about 5 minutes. Add 150 g butter in small pieces and knead until you get a smooth dough.
Cover and leave to rise for about 1 hour. In the meantime chop the chocolate finely. Roughly chop the nuts. Line two baking trays with baking paper.
Knead the dough well again with lightly floured hands and roll out into a rectangle (approx. 50 x 30 cm) on a floured work surface. Cut in half lengthwise. Cut the dough strips into 9 triangles each (lower edge approx. 10 cm long).
Spread 1 teaspoon of caramel cream on the lower sides of each triangle. Sprinkle with chocolate and roll up into croissants from below towards the tips. Spread on the baking trays. Cover and leave to rise in a warm place for another 30 minutes.
Preheat oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer). Whisk egg yolk and 1 tbsp. milk. Spread a thin layer on the croissants and sprinkle with nuts. Bake in a hot oven for approx. 12 minutes.