Warm the flour slightly. Make a well in the center and place salt and sugar around the edge. Crumble the yeast into the center and pour a little lukewarm milk over it. Let rest in a warm place for about 15 minutes until bubbles form.
Add the remaining lukewarm milk, egg yolks, vanilla sugar, orange zest and rum, then mix in the melted butter. Knead into a smooth dough (by hand or mixer) until elastic. Let rest covered in a warm place for about 20 minutes.
Shape into 12 balls, flatten slightly, fill with apricot jam and seal היט. Place in a greased baking dish seam-side down, close together, brush with melted butter and let rest another 15 minutes.
Bake at 180°C for about 30 minutes. Let cool slightly and serve warm, dusted with powdered sugar. Best served with vanilla sauce.