Preheat oven to 435 degrees F.
Peel the onion and cut off the top and bottom. Cut into wedges (eighths). Set aside.
Wash, core and cut the tomatoes into halves. Cut very large tomatoes into quarters. Cherry tomatoes or other small tomatoes can be left whole.
Scoop the seeds out of the tomatoes and discard or save for planting (the seeds are bitter and don't blend well).
Spread the tomatoes, garlic and onions onto a baking tray. Skin side up or down doesn't matter. Drizzle with oil and season with salt. Roast for 20 to 30 minutes. (Smaller tomatoes take less time; keep an eye on them to prevent burning)
Remove roasted tomatoes, garlic and onion from the oven. Let rest until they are cool enough to touch. Peel the tomatoes (the peels should slip off easily) and the garlic.
Transfer tomatoes, 4 or 5 cloves of the roasted garlic, onions, and pan juices to a large soup pot. (Save the extra roasted garlic for other uses)
Add the chicken stock, bay leaf, and herbs. Bring to a boil.
Reduce heat and simmer for 15 to 20 minutes.
REMOVE THE BAY LEAF and stir in the sugar if desired; it's to cut the acidity so it may not be needed depending on your tomatoes.
Use an immersion blender to puree the soup until smooth. Return soup to low heat and add cream, if desired.