Fry the cubed bread in the butter until it is golden brown.
Remove the bread and fry the onion in the same pan until it is soft and golden.
In a bowl, mix the milk with the egg and the yolk.
Season with salt and gradually add the flour, the fried bread, onion and pieces of ham.
Let stand for 15 minutes or so.
Form dumplings with a spoon and simmer in a large pan of salted water for 15 to 20 minutes.