Trim the tops off 4 of the heads of garlic. Just enough to expose all its cloves. Pour ½ tablespoon olive oil over the exposed cloves and sprinkle with a little salt and pepper. Place each bulb right side up on a small square of foil. Fold the foil around the bulb of garlic and place on a cookie sheet. Roast the garlic for 45 minutes. Cool thoroughly.
In a large pot, cook diced pancetta over medium heat until crispy, about 5-7 minutes. Drain off all but 1 tablespoon of pancetta fat. Reserve crispy pancetta in bowl. Add chopped onion to pancetta drippings in pan. Sauté onions until they start to caramelize, about 10 minutes.
When roasted garlic is cooled, press it out of its skins. Add it to a blender along with the chicken stock and cooked onions. Purée the soup until smooth.
Return soup to the pot, add kale and parmesan and bring to a simmer until kale is tender. Add cream and heat until desired temperature. Sprinkle the pancetta evenly among bowls and serve.
