Warm the milk lukewarm. Crumble yeast into it and dissolve while stirring. Put flour, sugar, 1 pinch of salt and egg in a bowl. Add yeast milk. Stir in with the dough hooks of the mixer, kneading butter in flakes until the dough is smooth.
If it forms a ball, continue kneading for about 3 minutes. Cover and leave to rise in a warm place for about 40 minutes until its volume has doubled.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Melt 50 g butter. Mix sugar and cinnamon. Briefly knead the yeast dough on a little flour and roll out into a rectangle (approx. 35 x 60 cm).
Spread the pastry plate with butter and sprinkle with cinnamon sugar. Cut the dough sheet in half crosswise and roll it up from the long side.
Cut each roll into about 10 pieces. Place snails on two baking trays lined with baking paper. Cover them and let them rise for about 10 minutes. Spread the rest of butter in flakes on the snails. Bake both trays one after the other in a hot oven for about 12 minutes.
Remove and let it cool down.