Preheat oven to 400.

Line 2 baking sheets with foil.

Wash and cut tomatoes lengthwise. Cut onions into thin slices.

Lay tomatoes face up on baking sheet. Drizzle with olive oil and season with salt and pepper. Do the same with the onions.

Prep the garlic. Leave head intact. Peel away outer layers and chop off tips of each clove. Brush with olive oil, wrap in foil cut side up, and place in small ceramic or glass baking dish.

Put tomatoes, onion, and garlic in the oven. Take out onions when they begin to brown, about 20 to 30 minutes. Take garlic out after it has been in the oven for about an hour. Let the tomatoes cook for a total of one hour and a half.

Put onions, garlic, and tomatoes in a large stock pot. Add cream, chicken broth, tomato paste, and basil. Stir well, bring to a boil then simmer for 5 to 10 minutes.

Using blender or immersion blender, puree soup. Stir in parmesan cheese just before serving.