In a large skillet over medium high heat add the Italian sausage and cook until no longer pink breaking it into pieces as it cooks. Remove the sausage and set aside.
In the same skillet add the diced onions and cook until soft about 3-4 minutes. Then add in the garlic and cook another 30 seconds.
Pour in the chicken broth and turn up the heat and bring to a low boil.
Add in the frozen tortellini and cook according to the pkg directions using about 3-4 minutes for frozen.
Stir in the heavy cream.
Add back in the cooked sausage, baby spinach, and Parmesan cheese and simmer until the spinach begins to wilt after a couple of minutes. The sauce will thicken as it cools a bit.
Add the red pepper flakes and salt, and pepper to taste! Serve