Remove the skin and excess fat from the duck pieces, dice the skin and fat into small pieces and set them aside. Sprinkle the skinless duck pieces evenly with 1 tablespoon plus 1 teaspoon of Meat Magic® and rub it in well.
Place the diced skin and fat into a heavy 4-quart pot over low heat and cook slowly, stirring every 1 or 2 minutes, until the skin has rendered as much fat as possible and is very crisp. The time to render the fat will vary widely, depending upon on how much fat there is. Be careful not to let the skin burn, as it browns very quickly--you want to render all the fat but not burn it. If you see blue smoke, lower the heat immediately. When the fat is rendered and the skin is just crisp and brown, turn off the heat and carefully pour the rendered fat and crisp skin (cracklings) into a strainer over a bowl. Set the drained crackling aside on paper towels, and reserve the duck fat.
To the now empty pot add ½ cup stock and stir and scrape the bottom thoroughly to loosen all the browned bits. Pour this stock, with the brown bits (they add great flavor) back into the container that holds the rest of the stock. Wash the pot and dry it, then pour the reserved duck fat back into the clean pot and place it over high heat. When the fat is hot, brown the duck in batches, turning once a minute, for 7-8 minutes per batch. Remove the duck from the pot and set it aside. To the same pot, add ¾ cup stock, the flour, and the remaining Meat Magic®. If the flour forms lumps, use a whisk to break them up. Cook, almost constantly stirring and scraping the bottom of the pot, until the mixture is lightly browned and sticks hard, about 3-4 minutes. Add 1 cup of stock, scrape the bottom of the pot to loosen the brown bits, and add a little more stock if necessary. Add the onions, celery, and 1½ cups of stock. Return the duck and the accumulated juices to the pot together with any remaining stock. Bring just to a boil, reduce the heat to low and simmer until the duck is tender, about 15 minutes. Add the cauliflower and submerge it completely into the liquid. Cook, scraping the pot bottom once or twice until the cauliflower is tender, about 6 to 8 minutes. Stir in the cream, then bring just to a boil and remove from the heat.
For each main course portion, serve 1½ cups of soup with ½ cup rice and 2 pieces of duck, and for an appetizer portion, serve ¾ cup of soup with ¼ cup of rice and 1 piece of duck. If you prefer, you can serve the duck on a plate alongside the soup in its bowl. Or, if you like a hearty soup that's easy to eat, once the duck is done and cool enough to handle, cut the meat off the bones and return it to the soup. Garnish with the green onions and crackings.