Make a yeast dough from the dough ingredients and let rise. Roll out 2/3 of the dough on a greased baking sheet. Prick the dough several times with a fork.
For the poppy seed topping, bring the water / milk to the boil, add the poppy seeds, semolina, sugar, cinnamon, salt and bring to the boil again (if too liquid, mix in some semolina or breadcrumbs). Mix in the almonds, nuts, flavor and desiccated coconut and allow to cool.
Beat the egg white until stiff and mix it carefully into the poppy seed mixture. Smooth on the yeast dough.
Roll out 1/3 of the yeast dough and carefully transfer onto the poppy seed topping. The poppy seed mass should no longer be visible.
Melt the butter, knead with the flour, vanilla sugar and sugar to make a crumble and shape into a ball.
Mix 20 ml milk with 1 teaspoon sugar and brush the yeast dough with it, pricking again several times with a fork.
From the still warm crumble dough (important, the crumble dough must still be warm), pluck small biscuits approx. 2 cm with 2 fingers and spread them next to each other on the cake (if the crumble dough is too crumbly, too dry, add a little fat or 1 egg yolk) .