Bring plenty of salted water to a boil in a large saucepan.
Peel onions and cut into rings. Melt 30 grams of butter in a frying pan and fry the onions in it gently over medium heat until golden brown.
Stir through eggs, milk, flour, salt and nutmeg. Grate the dough with a spaetzle slicer into the boiling water on the spot and let it stand for a few minutes at low heat. The spätzle are done when they float on the surface.
Melt the remaining butter in a large frying pan. Remove the sparrows with a skimmer, drain and toss briefly in the butter. Turn off kitchen stove. Fold in the freshly grated cheese and let it melt briefly in the closed frying pan.
Divide the onions evenly among the sparrows and bring to the table on the spot.
Serve with: leaf salad