Stir yeast and 25 g sugar until the yeast becomes liquid. Put flour, salt, egg and 25 g sugar in a bowl. Melt 40 g fat and add the cold milk. Pour lukewarm fat-milk mixture to the flour, add yeast and knead with the dough hooks of the hand mixer to a smooth yeast dough. Cover and leave to rise in a warm place for about 30 minutes. In the meantime chop the chocolate very finely.
Melt 100 g fat. Briefly knead the yeast dough again and roll out into a rectangle (approx. 36 x 40 cm) on a floured work surface. Spread the dough with about half of the butter. Spread 400 g chocolate and chopped nuts on top, leaving a 2-3 cm wide edge on the sides. Roll up from a short side. Press the edge of the dough well. If necessary, press the roll into shape and cut it into slices/ snails about 1 1/2-2 cm wide and spread them on 2-3 baking trays lined with baking paper. Brush with liquid fat. Bake the trays with the snails one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes. Brush with butter in between. Remove the snails and let them cool down.
Press the edge of the dough well. If necessary, press the roll into shape and cut it into slices/ snails about 1 1/2-2 cm wide and spread them on 2-3 baking trays lined with baking paper. Brush with liquid fat. Bake the trays with the snails one after the other in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes. Brush with butter in between. Remove the snails and let them cool down. Melt the remaining chocolate over a warm water bath. Run the chocolate in strips over the snails
waiting time approx. 1 1/2 hours