1. For the dough, add milk, butter, and sugar to a small saucepan and gently heat up on the stove until the butter has melted, and the sugar has dissolved completely. Remove from the heat and let cool to about 96°F/36°C (lukewarm).

2. Add the flour to a large bowl (kitchen machine) and mix with the dry yeast and salt. Add the cooled mix and the egg yolks and knead for about 6-7 minutes until you get a nice and smooth dough that comes off the sides of the bowl. Shape the dough into a ball, cover, and let rise in a warm place for about 1 hour. The volume should double more or less. While the dough is rising, prepare the crumbles.

3. Preheat the oven to 350°F (180°C). Mix the flour for the crumbles with the brown sugar, rolled oats, and ground cinnamon in a bowl. Add the melted butter and mix in with a fork to create different-sized crumbles. Spread them on a baking sheet lined with baking parchment and bake for about 10 minutes or until the crumbles are crispy and nicely golden brown. Take out of the oven and let cool down completely.

4. Roll out the risen dough on a lightly floured surface (approx. the thickness of a finger). Use a cookie cutter or glass and cut out circles with a diameter of about 2.8 inches (7 cm). Collect scraps and roll them out again to get more dough circles. Place the dough pieces on a baking sheet (lined with baking parchment), cover with a damp kitchen towel, and let rise for another 20-25 minutes.

5. Heat up some fat/oil in a small pot until you get a temperature of about 350°F (175°C) – a thermometer* is very helpful here. If the temperature is too low, the dough will soak up fat – if the heat is too high, the dough will darken too quickly and not bake properly. Fry the dough circles (no more than 2-3 at a time) in the hot fat. Deep-fry the donuts first on one side for about 2 minutes, then flip them and deep-fry for another minute or so. Take them out of the fat /oil and let them drain on a piece of kitchen paper.

6. Mix confectioners’ sugar, vanilla paste, and a little milk in a small, shallow bowl. The glaze should be quite thick, so it doesn’t run off the donuts immediately – if necessary, add a bit more milk to thin out the glaze or confectioners’ sugar if it seems too thin.

7. Add the rhubarb curd to a piping bag fitted with a donut nozzle*. Fill the completely cooled donuts with curd and press them into the vanilla glaze. Place the glazed donuts on a cooling rack, sprinkle the crumbles on top, and let them dry for a few minutes. Serve as soon as possible.