Preheat oven to 220C. Place chicken bones and wings in a large roasting pan and roast for 30 minutes or until dark brown in colour. Combine bones and wings in a large saucepan with remaining ingredients and 4 litres of cold water. Bring to the boil, then reduce heat to medium and simmer, skimming occasionally, for 3 hours. Season to taste with sea salt. Strain through a fine sieve, reserve stock and discard solids. Makes about 3 litres.
For bone marrow dumplings, combine ingredients in a bowl and season to taste with sea salt and freshly ground black pepper. Using two teaspoons, shape mixture into dumplings, dipping spoons in hot water between each dumpling to clean, and refrigerate for 30 minutes. Makes about 18 dumplings. Bring a saucepan of salted water to a simmer over medium heat,
add dumplings a few at a time and simmer gently for 4-5 minutes or until they float, then remove with a slotted spoon and set aside. Repeat with remaining dumplings.
To serve, bring 2 litres of chicken broth to a simmer over medium heat, add dumplings and cook until warmed through. Ladle soup and dumplings into bowls and serve.