Melt the butter with olive oil in a large heavy Dutch oven or soup pot over medium heat. Add the diced onion, carrots, and celery. Sauté for 5 to 6 minutes until tender and translucent.

Stir in the minced garlic, Italian seasoning, kosher salt, and cracked black pepper. Cook for 60 seconds until fragrant, stirring continuously to prevent the garlic from browning. Sprinkle the flour over the vegetables and stir well for 1 minute to cook out the raw flour flavor.

Gradually pour in the warm chicken bone broth, whisking constantly to ensure no flour lumps form. Bring the broth to a rolling boil over medium-high heat, then reduce to a gentle simmer for 5 minutes.

Add the refrigerated three-cheese tortellini into the bubbling broth. Simmer uncovered for 3 to 4 minutes (tortellini should be just al dente and floating to the top; do not overcook).

Turn the burner heat down to low. Stir in the cooked shredded chicken breast and fresh baby spinach. Let the spinach gently wilt in the warm broth for 90 seconds.

Pour in the heavy cream and gradually whisk in the freshly grated Parmesan cheese until melted into a silky, velvety cream broth. Simmer gently for 2 minutes—do not let the soup boil after dairy is added.

Ladle hot into wide ceramic soup bowls. Top with extra shaved Parmesan, freshly cracked black pepper, and fresh parsley. Serve immediately with warm crusty garlic sourdough bread!