Cook spaghetti in boiling water in a large saucepan following packet direction, Drain set, aside and keep warm
To make filling, heat oil in a large frying pan and cook leeks and chicken stirring for 4-5 minute
To make filling, heat oil in a large frying pan and cook leeks and chicken striring for 4-5 minute or ubtil chicken is brown. Stir in stock , corn flour mixture mustard and basil an cook, stirring, for 2 minutes longer. Season to taste with black pepper
Place spoonfuls of filling on lasagna sheets, rolls up , top with parmesan cheese and serve.