Spray a large nonstick skillet with cooking spray and place over medium heat. Add the onion, celery, carrots and garlic. Add ½ cup of broth and bring to a boil. Cook, partially covered, stirring occasionally, until the broth has evaporated, about 10 minutes.
Add the turkey sausage and cook, stirring often and breaking up the meat with a spoon, until the sausage is cooked through, about 10 minutes. Stir in the poultry seasoning, salt and pepper.
Scrape the sausage mixture into a large bowl. Mix in the bread crumbs and parsley. Gradually stir in the liquid egg substitute (or egg) and about 1 cup broth, until stuffing is evenly moistened but not soggy.
Use as a stuffing. Or place in a lightly buttered casserole dish, drizzle with ½ cup broth, cover, and bake as a side dish at 375℉. for 30 to 45 minutes.