Preheat the oven to 400°. Line a medium sheet pan with aluminum foil and spray with nonstick cooking spray. Set aside.
Slice Roma tomatoes in half and add to a large bowl. Peel the onion and cut into quarters, remove the seeds in the red pepper and quarter, then add both the pepper and onion to the bowl. Drizzle in 3 tablespoons of olive oil, salt, pepper, oregano and red pepper flakes. Stir to make sure everything is evenly coated.
Pour the tomato mixture onto the prepared pan and spread evenly so each vegetable is flat on the sheet pan. Cut off the top of the head of garlic and drizzle in remaining 1 tablespoon of olive oil. Add to sheet pan and place on the middle rack of the oven. Roast for 45 minutes.
After the 45 minutes, remove the sheet pan from the oven. Using tongs, remove the roasted garlic and place on a dish to allow it to cool. Add all of the roasted tomatoes, onion and red pepper to a blender. Puree until smooth, about 30 seconds.
Once the garlic is cool enough to touch, squeeze out of the papery shells into the blender. Puree until smooth. Next add in the fresh basil and puree until blended, about 15 seconds.
Pour the mixture from the blender into a large pot. Add in 2 cups of chicken broth, 1 tablespoon of bouillon and bring to a simmer. Add salt and pepper to taste. If you'd like to add the heavy cream you can stir it in now or after you serve it! Serve hot and garnish with extra basil, and freshly grated Parmesan cheese.