Heat oil and butter in a skillet over medium heat. Sauté onion and garlic until onion is translucent. Set aside. Pour water in a stockpot and bring to a boil. Add chicken; season with salt and pepper. Cover; simmer for 20 minutes, or until chicken is tender. Take out the chicken and let it cool. Using your hands (or two forks – one to tear the chicken meat and one to hold the bone), shred the meat of the cooked chicken; discard the bones. Put shredded chicken back in the pot. Add sautéed onion and garlic, carrot, macaroni and sausages. Simmer over medium-low heat for 15 minutes, or until macaroni is tender. Add cabbage and milk; simmer for another 5 minutes. Serve in individual bowls and garnish with green onions. Serves 4 to 6.