01 - Heat olive oil in a large pot over medium heat. Add diced onion and cook for 4–5 minutes until soft and translucent.
02 - Add minced garlic and sauté for 1 minute until fragrant.
03 - Stir in tomatoes, vegetable broth, sugar (if using), salt, pepper, and oregano. Bring to a simmer.
04 - Cover and simmer for 20 minutes, stirring occasionally, until tomatoes are very soft and flavors are blended.
05 - Remove from heat. Add chopped basil.
06 - Using an immersion blender (or working in batches with a countertop blender), purée the soup until completely smooth.
07 - Return soup to low heat. Stir in the heavy cream and heat gently for 3–4 minutes—do not boil.
08 - Taste and adjust seasoning if needed. Serve hot, garnished with extra basil leaves.