This was delicious -- the family and I all loved it. I followed suggestions from multiple review and doubled the mustard (DO IT! It would have been a little bland without that.) and added sliced mushrooms to the leeks (a nice addition). Otherwise made this exactly as written. It's a great dish. The chicken was tender, and the favor of the broccoli was a terrific balance to the sauce. When I make it again (and I definitely WILL!), I might add just a little more flour ... the sauce seemed very slightly thin. But in general, this was a big winner, and the entire household loved it.