In a heavy-bottomed skillet, heat the olive oil over medium-high heat and add the garlic. Cook over medium-high heat two minutes, then add the guanciale, and cook until most of the fat has been rendered. Discard the excess fat and add the peas, sugar, and chicken stock.
Stir well, season with salt and pepper, and cook over high heat until the peas are tender and the liquid has reduced by about half. Adjust the seasoning and serve hot.
In a large, heavy-bottomed saucepan, heat the oil over high heat until smoking. Add all the chicken parts and brown all over, stirring to avoid burning. Remove the chicken and reserve. Add the carrots, onions, and celery to the pot and cook until soft and browned. Return the chicken to the pot and add 3 quarts of water, the tomato paste, peppercorns, and parsley. Stir with a wooden spoon to dislodge the browned chicken and vegetables bits from the bottom of the pan. Bring almost to a boil, then reduce heat and cook at a low simmer until reduced by half, about 2 hours, occasionally skimming excess fat. Remove from heat, strain, and press on the solids with the bottom of a ladle to extract out all liquids. Stir the stock to facilitate cooling and set aside. Refrigerate stock in small containers for up to a week or freeze for up to a month.
Yield: 1 1/2 quarts