Recipe from Family Celebrations with the Cake Boss by Buddy Valastro.
Heat a large, heavy pot over medium heat. Add the butter and cook until it is melted and foamy. Add the onion and garlic, and cook, stirring occasionally, until softened but not browned, about 4 minutes. Pour in the tomatoes and their juices then stir in the stock. Raise the heat to high, bring to a boil, then lower the heat so the liquid is simmering. Continued to simmer, stirring occasionally, until the tomatoes begin to break down, about 10 minutes. Set aside 2 tablespoons of the basil, and stir the rest into the pot.
Using an immersion blender, or working in batches in a standing blender*, purée the soup until almost smooth. Stir in the cream, season with salt and pepper, and adjust the consistency with more cream or chicken stock. Ladle into bowls and garnish with the remaining basil.