For the yeast dough, warm the milk lukewarm. Crumble the yeast into it, dissolve while stirring. Put 250 g flour, 50 g sugar, 1 pinch of salt, vanilla sugar and egg in a bowl. Add yeast milk. Stir in with the dough hooks of the mixer, kneading 30 g butter in flakes until the dough is smooth and soft.
When the dough separates from the bowl, continue kneading for about 3 minutes. Cover and leave to rise in a warm place for about 1 hour until its volume doubles.
For the compote, wash, halve and stone the plums. Cut the plums into small pieces. Mix with 2 pinches of cinnamon and 50 g sugar in a pot. Leave to stand for about 30 minutes. Then cover the plums and simmer for about 5 minutes over medium heat, stirring occasionally.
Stir starch and 2 tablespoons of water until smooth. Stir into the hot plums. Simmer compote for about 1 minute.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Grease an ovenproof pie dish (approx. 26 cm Ø) and dust with flour. Briefly knead the dough onto a little flour and roll out into a rectangle (approx. 30 x 40 cm).
Spread compote on it. Cut the dough into 3-4 cm wide strips. Roll up 1 strip like a snail and place it in the middle of the form. Place the remaining strips of dough one after the other at the end of each snail.
Bake in a hot oven for 20-25 minutes. Let the cake cool down. Stir the crème fraiche until smooth, fill into the freezer bag and cut off a small corner. Pour over the cake.