Add the Italian sausage to a large soup pot over medium-high heat.
Add the chopped yellow onion and break the sausage apart.
Cook for about 6 minutes until the sausage is browned.
Add the chicken broth, tomato sauce, Italian seasoning, garlic powder, salt, and pepper.
Stir and let the liquid come to a simmer.
Once simmering, add the frozen cheese tortellini, chopped baby spinach leaves, and heavy cream.
Stir and let simmer until the pasta is tender, about 3-5 minutes.
Serve with grated Parmesan cheese on top.
