Quarter your tomatoes and placed them on a lined baking sheet. Peel your garlic and add the whole cloves to your baking sheet as well.
Drizzle everything with olive oil and sprinkle with salt and pepper. Then place tomatoes and garlic in a 400° oven for 15 minutes.
Dice your onion, while the tomatoes and garlic are roasting.
Warm some olive oil (about one to 2 tablespoons) in the bottom of your Dutch oven or heavy bottom pot. Once the oil is warm, add the diced onions and cook until translucent.
Remove tomatoes and garlic from oven and add to the pot with the onions.
Add 2 cups of vegetable broth and fresh basil leaves. Bring to a boil, and simmer for about five minutes.
Blend using immersion blender or heat safe blender such as a Vitamix. Once desired consistency is reached, add heavy cream, salt, and pepper to taste.