Heat olive oil in a large pot over medium heat. Add the sausage, breaking it apart with a spoon. Cook until browned and fully cooked, about 5–7 minutes.
Stir in the chopped onion and cook for 3–4 minutes until softened. Add minced garlic and cook for another minute until fragrant.
Pour in diced tomatoes with juices and chicken broth. Stir well and bring to a gentle simmer.
Add cheese tortellini and cook according to package instructions, about 5 minutes, until tender.
Stir in chopped spinach until wilted, about 2 minutes. Reduce heat to low and stir in heavy cream and Parmesan cheese. Heat gently for 2–3 minutes, avoiding boiling.
Season with salt, black pepper, and red pepper flakes to taste.
Ladle soup into bowls and serve warm with slices of crusty bread for dipping.
