In a stockpot or large saucepan, heat the oil with with leek and the spices, garlic and chives. Saute until the leek begins to soften then add the sweet potato and the water.
Simmer for a few minutes, until the spices begin to dissolve then stir in the milk, corn, peas, capsicum and chicken. Simmer until capsicum begins to soften, about 30 minutes. Serve topped with grated cheese.