01 -
In a large pot over medium heat, melt the unsalted butter. Add the celery, onion, fennel, and 1/2 teaspoon salt. Cook, stirring occasionally, until the vegetables are softened and translucent, approximately 7 to 8 minutes.
02 -
Stir in the tomato paste and cook, stirring frequently, until it darkens in colour, about 2 minutes. Add the crushed red pepper flakes and cook, stirring, until fragrant, about 1 minute.
03 -
Add the whole peeled tomatoes with their juices, tomato juice, and light brown sugar. Bring the mixture to a simmer, mashing the tomatoes gently with a wooden spoon or spatula into large pieces. Cook, stirring occasionally, until the soup is slightly reduced, about 10 minutes. Remove from heat and let cool for 5 minutes.
04 -
Transfer half of the soup mixture to a blender and blend until completely smooth, or use an immersion blender to puree the soup in the pot. Pour the blended soup into a large bowl and repeat with the remaining soup. Return all puréed soup to the pot.
05 -
Stir in the heavy cream until fully integrated. Cook the soup over medium heat, stirring frequently, just until heated through—do not allow the soup to boil. Season with the remaining 1 1/2 teaspoons salt.
06 -
Distribute soup among bowls. Drizzle with additional cream and garnish with fresh basil leaves before serving.