Heat olive oil in a saucepan over medium heat. Add the chopped onions and garlic, sautéing them until they become translucent.
Add the diced tomatoes, salt, and pepper to the saucepan. Stir everything together, ensuring the tomatoes are coated well. Let it simmer until the tomatoes soften.
Pour in the vegetable broth. Bring the mixture to a boil, then reduce heat and let it simmer.
Stir in fresh basil leaves. Using an immersion blender, blend the soup until smooth.
Add cream while stirring to achieve a luxurious texture.
Notes
Store any leftover soup in the refrigerator for up to 4 days, or freeze for up to 3 months. Reheat gently before serving.