In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for about 5 minutes until softened. Stir in the minced garlic and cook for an additional 1 minute until fragrant.
Pour in the vegetable broth and add the diced tomatoes, Italian seasoning, salt, and black pepper. Bring the mixture to a boil.
Once boiling, add the cheese ravioli and reduce the heat to a simmer. Cook according to package instructions, usually about 4-5 minutes, until the ravioli are tender.
Stir in the heavy cream and fresh spinach. Cook for an additional 2-3 minutes until the spinach is wilted and the soup is heated through.
Remove from heat and stir in the grated Parmesan cheese until melted and well combined.
Serve hot, garnished with fresh basil leaves if desired.