- Heat a pot over medium heat. Add butter then add chopped onions. Sauté 10-12 minutes, stirring occasionally, until softened and golden. Add minced garlic and sauté 1 minute until fragrant. Add crushed tomatoes with their juice, vegetable stock, chopped basil, sugar, and black pepper. Stir together and bring to a boil then reduce heat, partially cover with lid and simmer for 10 minutes. Then blend it. then return blended soup to the pot over medium heat. Add 1/2 cup heavy cream, 1/3 cup freshly grated parmesan cheese and return to a simmer. Season to taste with salt and pepper and turn off the flame. Garnish with cream and serve hot.