Heat the olive oil in a large soup pot over medium heat. Add the yellow onion and carrots. Cook for 6 to 8 minutes, stirring, until the onion is translucent and the carrots begin to soften.

Add the garlic, tomato paste, and dried Italian seasoning. Stir for 1 minute, until fragrant and the tomato paste darkens slightly.

Add the diced tomatoes with their juices, low-sodium vegetable broth, fine salt, and black pepper. Bring to a gentle boil, lower the heat, and simmer uncovered for 10 minutes, until the carrots are tender.

Add the refrigerated cheese tortellini. Simmer gently for the package cooking time, usually 3 to 5 minutes, stirring occasionally so the pasta does not stick. A cut piece should be tender through the center.

Reduce the heat to low. Stir in the heavy cream and baby spinach. Warm for 2 minutes, until the spinach wilts and the soup is hot, without letting it boil hard.

Taste the broth and add a little more fine salt or black pepper if needed. Ladle into bowls and serve promptly so the tortellini keeps its shape.