This is a tough one. Starts inside La Chambre and is pretty steep immediately. Things stay that way for the whole 19km. There is the odd 5% bit (which feels like flat in comparison).
Lots of traffic too. Eventually you arrive at a large ski resort and once you are through that the traffic reduces dramatically. It also gets picturesque for the first time.
Lots of cafe options at the top. Descent back down was difficult - all those 8 to 10% drops mean you are constantly picking up serious speed going into hairpins all the way down.