In a frying pan at low temperature, fry the bacon in the oil, a little later add the onions and leeks and sauté until translucent.
Season with salt and pepper, remove from the frying pan and cool.
Heat half of the milk to 30°C, let the yeast melt in it and sprinkle in the sugar. Sift the flour into a suitable bowl and press a small indentation in the center. Pour in the yeast milk, mix with a little flour and sprinkle a little flour on top. Cover the dampfl with a kitchen towel and leave at room temperature for fifteen min.
Add the bacon-onion-porridge mixture with the remaining milk, beaten egg and egg yolk and salt to the flour form and mix everything together. Add the softened butter and knead with a wooden spoon or in a food processor to form an elastic dough. Cover with a kitchen towel and let rise at room temperature for at least thirty minutes, until the dough has doubled in size.
Mix the dough heartily with a wooden spoon. With a floured spoon, cut out large pieces of 50 to 60 g on the spot, place on a well-floured tea towel, dust with a little flour and shape each piece into a ball. Cover with a second kitchen towel and let rise for another fifteen min.
In a shallow saucepan (about thirty cm in diameter) heat clarified butter, butter and milk and place the dough balls in it. Cover and cook at low temperature on the heated stove.