Preheat oven to 400°.
Trim crust from bread. Cut bread into 1 1/2-inch cubes. Arrange bread cubes in a single layer on 2 jelly-roll pans. Bake at 400° for 10 minutes or until toasted.
Reduce oven temperature to 350°.
Cook sausage in a large nonstick skillet over medium-high heat 10 minutes, browning on all sides. Remove from pan; cut crosswise into 1/4-inch-thick slices.
Melt butter in skillet over medium-high heat. Add mushrooms; sauté 4 minutes. Combine bread cubes, sausage, and mushrooms in a large bowl.
Heat skillet over medium-high heat. Coat pan with cooking spray. Add onion, carrot, and celery; sauté 5 minutes or until lightly browned. Add parsley, thyme, sage, salt, and pepper; sauté 1 minute. Add to bread mixture. Combine eggs and broth, stirring with a whisk. Add to bread mixture; toss to coat. Spoon into a 13 x 9-inch baking dish coated with cooking spray. Bake at 350° for 45 minutes or until browned.