Haven't posted a recipe in a while, so here goes.
Take some chicken. Chose your weapon, but I think boneless skinless breasts are one of the great advances of the twentieth century. I like my chicken that way, too.
Onion (or not--it's an option)
A couple of leeks
Cut the leeks into about one inch pieces and wash well. Heat some oil, saute the garlic (and onion) then add the chicken. Cook the chicken until almost done. Add around a half cup of white wine and the leeks. Cook until the chicken is done and the leeks are heated through. Move the chicken and leeks to a plate. Add some heavy cream to the pan to make a sauce and add a tablespoon or so of mustard to the sauce. Pour over chicken and leeks, toss to coat and enjoy.
I recommend using an extra large bottle of wine so that there's still plenty left to drink with dinner...