Pour olive oil in Dutch oven and on medium-high heat cook onions for 3-5 minutes. Add garlic and cook for 40 more seconds until fragrant. Add crushed tomatoes, chicken stock, heavy cream, and stir together. Let simmer for 30 minutes - 2 hours. Add basil, salt, and pepper, and stir until wilted. Pour into soup bowls with parmesan cheese to top (optional).