Sage, Sausage and Apple Dressing

Name: Sage, Sausage and Apple Dressing
Cook time: 20 min
Total time: 20 min
Cuisine: American
Ingredients: One 16-ounce bag stuffing cubes; 6 tablespoons unsalted butter, plus more for greasing the pan and topping; 1 pound fresh sage sausage, casings removed; 1 medium onion, chopped; 2 cooking apples, such as Gravenstein, Rome, or Golden Delicious, peeled, cored, and chopped; 1 to 2 ribs celery with leaves, chopped; Kosher salt; 3 cups chicken broth, homemade or low-sodium canned; 1/4 cup chopped fresh flat-leaf parsley; 1/2 cup walnut pieces, toasted (see Cook's Note); 2 large eggs, beaten