In a skillet, cook the sausage over medium heat until browned. Drain any excess grease.
Add the cooked sausage to the Crockpot.
Pour in the marinara sauce, heavy cream, garlic powder, and Italian seasoning. Stir until well mixed.
Add the tortellini and toss gently to coat.
Cover and cook on LOW for 4–6 hours or on HIGH for 2–3 hours until the tortellini is tender.
About 30 minutes before serving, stir in the spinach, mozzarella, and Parmesan.
Taste and season with salt and pepper as needed.
Serve hot, with extra cheese sprinkled on top if you’re feeling fancy.