Place a large skillet over medium heat and add sausage. Break sausage into small pieces and cook until mostly browned (it will continue to cook in the crockpot). Drain off excess grease.
Add sausage, vegetables, seasoning, and broth to the slow cooker and stir to combine.
Cover and set slow cooker to high for 4-5 hours or low for 6-8 hours.
Serve hot with parmesan and extra red pepper flakes.