Chicken and leeks in white sauce. Best way to cook the chicken?

[Tortoise]

Can i make the white sauce and cook the leeks and chicken in it? If so, how long to cook it for? And will it need to go into the oven too?
Or should i do it in a frying pan 1st?

Bump

It sounds yummy.
I would cook white sauce separate to avoid the risk of milk curdling. Having said that I have cooked meat and fish in the past in milk, then strained the milk and used the serum(ish) to create a sauce.

Well,i have fried the chicken and made sauce separately. All mixed together. Now topped with mash and a bit of grated cheese and ready to pop in the oven to brown the top.

Thanks for reply though.