Heat a large dutch oven or soup pot over medium heat. Add the olive oil and Italian sausage. Crumble and cook the sausage until it is fully brown.
Add the onion and garlic to the pot. Stir and sauté for 3 minutes or until onion has softened and is translucent.
Next add the Italian seasoning, salt, garlic powder, black pepper, tomato paste, and diced tomatoes to the pot. Stir everything together with the Italian sausage.
Pour the chicken broth into the pot and stir. Cover the pot with a lid, bring the pot to a gentle boil, and boil for 10 minutes.
After 10 minutes add the cheese tortellini pasta to the pot. Gently stir, then place the lid back on the pot and boil for 4-5 more minutes.**
While the tortellini pasta is boiling, combine the heavy cream and cornstarch in a measuring cup. The cornstarch is optional-see note below. Mix well.
Once the tortellini pasta has boiled for roughly 5 minutes, turn the heat off and stir in the heavy cream mixture into the pot. Finally add the baby spinach to the pot and stir. The residual heat will help the spinach wilt down into the soup.
Serve this creamy tortellini soup with freshly grated parmesan cheese and chopped parsley on top. Enjoy!