Preheat oven to 350 degrees. Spray a 9 x 13 pan with nonstick cooking spray. Add cubed bread to a large bowl, set aside.
Melt butter in a large skillet. Add in onion, carrot and celery and saute until tender and golden brown, 4-5 minutes. Add in garlic and cook for an additional minute. Remove from the pan and add the veggies to the cubed bread.
Add sausage to the same skillet as the veggies and brown, 4-5 minutes. Making sure to break up the sausage as it cooks.
Add the broth to the skillet and scrape the bottom of the pan to deglaze the pan. Pour the sausage and broth into the large bowl with the bread along with the egg, herbs, salt and pepper. Gently toss to combine.
Pour mixture into the prepared pan and bake for 60 minutes or until golden brown on the top. (If you find the top getting too browned place aluminum foil on top). Serve warm with more fresh chopped parsley for garnish, if desired.