For scalloped dumplings, cook dumplings in salted water according to package directions, strain. Cut the smoked bacon into very small cubes and fry in a hot pan.
Peel and halve the onion, cut into fine rings and fry with the smoked bacon until light brown. Cut the mozzarella into small cubes.
Put a layer of dumplings in a baking dish, put some of the bacon and onion mixture on top, and some of the mozzarella, then dumplings again, etc. Finish with mozzarella.
Bake in the preheated oven at medium heat until the cheese has a nice color.