Preheat the oven to 400 degrees. Toss the whole tomatoes with about a tablespoon of olive oil, then season liberally with salt.
Bake for 25-30 minutes until the tomatoes start to burst and blister in parts. Remove from oven and cool slightly.
Pour the tomatoes & their juices into the blending beaker if using an immersion blender and add chicken broth. Blend to desired consistency.*
Pour the blended soup into a saucepan over medium heat, and add smashed garlic cloves and basil leaves. Bring up to a simmer and cook for about 10-15 minutes.**
Remove smashed garlic cloves and wilted basil leaves, or blend the basil into the soup directly in the pot with your immersion blender.
Serve hot with croutons, crackers or a hot grilled cheese. Mmm....