Fry the slices of bread in butter on both sides. Break one egg on top of each of the bread slice without breaking the yolk. Cover with plenty of Parmigiano. Bring the broth to a boil and pour it slowly over the eggs. The eggs will cook fast. Serve immediately.
Note:
You may also fry the eggs in butter before placing them on the slices of bread, and then cover with hot broth.