In a large pot, heat 2 tablespoons of olive oil over medium-high heat. Add the Italian sausage and cook for 5-7 minutes until browned, then drain excess grease.

Lower heat to medium and sauté 1 chopped yellow onion for about 5 minutes until softened. Add minced garlic, Italian seasoning, and red pepper flakes, cooking for another minute.

Pour in 4 cups of chicken broth and add diced tomatoes. Bring to a simmer over medium-high heat for 3-4 minutes.

Cover and reduce heat to low, letting it simmer for about 15 minutes while stirring occasionally.

Add 2 cups of thawed frozen chopped spinach, stirring until heated through, about 3 minutes.

Stir in 9 ounces of cheese tortellini and cook according to package instructions, usually 3-5 minutes.

Reduce heat to low, mix in 1 cup of heavy cream and ½ cup of grated parmesan cheese until incorporated.

Season with salt and black pepper to taste, adjusting gradually.

Serve hot, garnished with fresh parsley and additional parmesan if desired.