Heat olive oil in a large pot over medium heat. Add diced onion and fennel, cooking for 5-6 minutes until soft.

Stir in minced garlic and cook for an additional minute until fragrant.

Add Italian sausage, breaking it apart as it cooks for about 5-7 minutes until browned.

Carefully drain excess grease and add crushed tomatoes and chicken broth, stirring well. Bring to a boil for 2-3 minutes.

Reduce heat to medium-low and simmer uncovered for 10-12 minutes.

Add cheese tortellini and cook for 3-5 minutes until tender.

Lower heat and stir in heavy cream, heating through for 1-2 minutes.

Toss in fresh spinach and stir until wilted, about 1-2 minutes.

Season with salt and black pepper to taste before serving.

Ladle soup into bowls and garnish with grated Parmesan cheese.