On a lined baking sheet, toss tomato halves with 2 Tbsp. olive oil, salt and pepper. Roast for 25-30 minutes.
Meanwhile, in a large pot, heat 1 Tbsp. olive oil over medium heat. Add chopped onion and cook 7 to 8 minutes, or until onions are golden brown. Add garlic and cook for 1 more minute. Add canned tomatoes and chicken broth, and increase heat to medium-high. Bring to a boil, reduce heat to medium and simmer for 20 minutes.
Remove roasted tomatoes from oven. To the soup add roasted tomatoes, whole basil leaves, salt and pepper. Remove from heat.
Using an immersion blender or food processor, puree soup until mostly smooth. Pour soup through a sieve into another medium pot.
Parmesan Crisps
Set pot to medium heat and simmer soup for 2 minutes. Add heavy cream, stir and remove from heat. Serve, topping with additional basil leaves and Parmesan Crisps (recipe below), if desired.
Preheat oven to 400 degrees F.
Place 4 tablespoons Parmesan onto a silicone or parchment lined baking sheet. Space each tablespoon about an inch apart. Lightly pat down with your fingers.
Bake for 3 to 5 minutes, or until golden and crisp. Allow to cool.