Apple-Walnut Sausage Stuffing

Ingredients
1 Lb. sausage
1/4 Cup butter or margarine
8 Oz. mushrooms, coarsely chopped
1 Large onion, chopped
2 Ribs celery, sliced
1 Large apple peeled, cored and diced (such as Braeburn and Gala)
2 Cups crushed herbed stuffing mix
2 Cups onion-sage crouton stuffing mix
1/2 Cup chopped walnuts or pecans (optional)
1 1/3 Cup chicken broth, heated
1 Egg, well beaten

Directions
Preheat oven to 325°F. Lightly grease 2-quart casserole or shallow baking dish. Meanwhile, cook sausage in large skillet; set aside in very large bowl. Melt butter in same skillet. Add mushrooms, onion and celery. Cook 4 minutes, stirring occasionally. Stir in apple; cook, stirring constantly, 2 minutes. Add to sausage in bowl.
Add stuffing mixes and nuts, if desired, to sausage mixture in bowl; toss to mix. Add broth and egg, tossing well.
Spoon into casserole or baking dish. Cover and bake for 20 minutes. Remove cover; bake 25 to 30 minutes more or until center is 165°F.