For the crumble mix butter with sugar, knead with flour and cinnamon, chill. Cover the baking sheet with parchment paper.
For the dough, mix the flour with the yeast, sugar, grated lemon zest and vanilla sugar. Add the butter, yolk, egg and milk and knead until a smooth dough is formed.
Press the dough evenly thick on the baking sheet, cover and let rise for about 1 hour.
Preheat the pipe to 160 ° C. Brush the dough with jam to taste. Halve the plums and stone them. Cover the dough with it, rub the crumble over it. Bake the plum stain in the oven for about 50 minutes.