Mix the milk, yeast and sugar together until the yeast is dissolved. Add the flour, egg and salt and knead everything into a dough. Add 3 tablespoons of butter and knead again for about 8 minutes.
Divide the dough and roll it into small balls. Place cups on a tray or choose a muffin pan and add one scoop at a time. Cover and let rise in a warm place for 30 minutes.
Preheat the oven to 180 ° C top / bottom heat and bake the donuts for 16 minutes. Let cool a little, then inject the jam.
Brush the donuts with melted butter and dust them immediately with powdered sugar.