2 1/2 pounds (about 2 loaves) high quality sandwich bread or soft Italian or French bread, cut into 3/4-inch dice, about 5 quarts
8 tablespoons (1 stick) butter
1 1/2 pounds sage sausage, removed from casing
1 large onion, finely chopped (about 2 cups)
4 large stalks celery, finely chopped (about 2 cups)
2 cloves garlic, minced or grated on microplane
1/4 cup minced fresh sage leaves (or 2 teaspoons dried sage leaves)
32 ounces (4 cups) low-sodium chicken or turkey broth, preferably homemade
3 whole eggs
1/2 cup minced parsley leaves
Kosher salt and freshly ground black pepper