Preheat oven to 400°F. Line baking sheet with parchment paper.
Gently toss 3 pounds halved tomatoes and 1 peeled and halved onion with 2 tablespoons of olive oil. Place on baking sheet.
Spray olive oil on top of the exposed side of garlic bulb. Sprinkle salt and pepper on top of the vegetables. Roast for 30 to 40 minutes.
In a blender, add 1 cup of stock, 1 garlic bulb pulp (Note: Squeeze the garlic with a garlic press or by hand for the pulp.), roasted onions, and roasted tomatoes. Blend well.
In a pot, heat remaining olive oil and butter. Add pureed vegetables and pour in remaining stock. Let it come to a boil.
Add to pot ¼ teaspoon crushed red pepper, ¼ teaspoon cayenne pepper, 1 teaspoon thyme, and 5 - 6 chopped basil leaves.
Pour ¼ cup cream into the pot. Let it cook for a few minutes.
Add salt and pepper to taste.
Serve with grilled cheese or toasted bread.