Pour the flour in the wide bowl of the food processor, pour in the yeast dissolved in a tiny bit of lukewarm milk, add a pinch of sugar, mix with a tiny bit of flour and leave with the lid closed for ten min until this so-called steam bubbles.
Then add the remaining ingredients – the butter should be room-warm and cut into flakes – and knead the food processor until the dough is silky smooth and comes away from the edge of the bowl absolutely smooth. Embed in a baking bowl dusted with flour and leave with the lid closed for an hour until the dough has more than doubled in size.
Meanwhile, for the filling, mix the ground poppy seeds with plum jam, vanilla sugar and powdered sugar until smooth and perfume with plum water.
Roll the risen dough repeatedly on a floured surface. Form into a roll, cut inch-thick slices into small pieces, flatten them a tiny bit and place a teaspoon of filling in the center of each, gather the dough over it and seal. Place on a floured board with the seam facing down. Make sure the dumplings are spaced apart, as they will now have to rise a second time and will almost triple in size. Cover the dumplings with a dishcloth and keep warm.
Finally, place the yeast dumplings one after the other on a steamer insert and cook over steam for about eight minutes.
For the sauce, mix milk and whipped cream