Preheat oven to 350F.
Bring the milk to a boil and cook gnocchi until tender. Drain about a half a cup of milk from the pot.
In the same pot as the gnocchi and milk, add 1 tablespoon butter, salt, pepper, bacon, onions, 2 cups of quattro formaggio, 1 cup cheddar and mix.
Put mixture into a baking pan and cover the top with breadcrumbs and remaining butter (cut into smaller pieces), quattro Formaggio and cheddar. Bake until brown and crispy on top.
Put mixture into a baking pan and cover the top with breadcrumbs and remaining butter (cut into smaller pieces), quattro Formaggio and cheddar. Bake until brown and crispy on top.