1. 1. Saute the Aromatics: In a large pot or Dutch oven, heat the olive oil over medium heat. Add the chopped onion and cook, stirring occasionally, until it softens and becomes translucent, about 5-7 minutes.

2. 2. Infuse with Garlic: Add the minced garlic to the pot and cook for another minute until fragrant. Be careful not to burn the garlic, as it can turn bitter quickly.

3. 3. Build the Broth Base: Pour in the chicken broth, then add the undrained diced tomatoes, Italian seasoning, salt, and black pepper. Stir everything together to combine.

4. 4. Simmer and Flavor: Bring the soup to a gentle simmer, then reduce the heat to low, cover, and let it cook for 10 minutes. This allows the flavors to meld beautifully.

5. 5. Cook the Tortellini: Uncover the pot and add the refrigerated tortellini. Increase the heat slightly to maintain a gentle simmer and cook according to package directions, usually 3-5 minutes, until the tortellini are tender but still firm to the bite.

6. 6. Add Cream and Spinach: Remove the pot from the heat. Stir in the heavy cream and the fresh spinach. The residual heat from the soup will be enough to wilt the spinach perfectly.

7. 7. Taste and Serve: Taste the soup and adjust seasonings if necessary. Ladle into bowls and serve immediately, garnished with grated Parmesan cheese if desired.