In a large pot, combine diced red onions, butter, and minced garlic. Saute for 5 minutes.
Add all remaining ingredients except heavy cream and parsley. Return to boil and then reduce heat to simmer, until yams are tender, about 45 minutes. Remove bay leaves and cinnamon stick. With an immersion (handheld) blender, blend soup to puree. Leave small pieces of yam if you like.
Add heavy cream and chopped Italian parsley and stir. Season to taste with salt and pepper.