If you're looking for the best tomato soup recipe, you've found it! Bursting with bright tomato flavor, this easy-to-make soup is the perfect partner for a gooey grilled cheese.
In a 6-quart stockpot or Dutch oven, heat oil, butter and pepper flakes over medium heat until butter is melted. Add carrots and onion; cook, uncovered, over medium heat, stirring frequently, until vegetables are softened, 8-10 minutes. Add garlic and basil; cook and stir 1 minute longer. Stir in tomatoes, stock, tomato paste, sugar, salt and pepper; mix well. Bring to a boil. Reduce heat; simmer, uncovered, to let flavors blend, 20-25 minutes.
Remove pan from heat. Using a blender, puree soup in batches until smooth. If desired, slowly stir in heavy cream, stirring continuously to incorporate. Return pan to stove to heat through. Top servings with fresh basil and Parmesan cheese if desired.