Melt the butter in a saucepan.
Add the onion and green pepper and fry until softened.
Stir in the flour and cook for 2 minutes, then gradually stir in the stock.
Bring to the boil and simmer, stirring frequently, for 5 minutes.
Add the potatoes, chicken and sweet corn and cook gently for 10 minutes or until the ingredients are heated through.
Add salt and pepper to taste, then stir in the milk or cream.