Warm the milk slightly. Crumble yeast into it, dissolve. Press a depression into 275 g flour. Add yeast milk and 2 teaspoons of sugar, mix with some of the flour to make a pre-dough. Cover and leave to rise in a warm place for about 20 minutes
Melt 25 g butter and cool. Add to the pre-dough with egg and 1/2 teaspoon salt, knead until smooth. Cover and leave to rise for about 30 minutes
Knead the dough on a little flour and quarter it. Shape each portion into a ball, adding 1 teaspoon of plum jam in the middle. Place on a floured board, cover and leave to rise in a warm place for about 20 minutes
Bring about 200 ml of lightly salted water to the boil in a wide saucepan. Hang the dumplings in on a steam or perforated insert. Steam covered for about 20 minutes. Take out dumplings and prick. Mix poppy seeds and 3 teaspoons of sugar and sprinkle on the dumplings. Melt 2 tbsp. butter and drizzle over the dumplings. Serve with vanilla sauce