In a medium skillet, cook sausage links according to package directions (approximately 10 minutes). Transfer cooked sausage links to a plate and cut into bite-size pieces. Add the onion, bell pepper and mushrooms to the skillet (do not remove sausage grease) and cook over medium heat, stirring, for 3 to 5 minutes or until veggies are soft and fragrant.
In a medium bowl, whisk the eggs, 1 cup of cheese and parsley together. Add to skillet and cook, stirring often, for 8 minutes or until eggs are cooked through. Add sausage pieces and cook until warmed through. Top with remaining 1/2 cup of cheese and serve warm.