I have never been able to prepare a recipe in the time they claim it takes and I have been cooking for many years. You're right, they have sous chefs who do all the mis en place for them and then they just assemble. However, with a recipe like this one, I'm thinking you could make it ahead when you have a whole free afternoon and then freeze it for later.
Like the other review said, be prepared to spend some time on this, but oh my goodness is it worth it. Delicious. Can't say it enough. I made it for a dinner party and, although I'm bias, believe it tasted like something from a snazzy restaurant. I added a heap of chopped, fresh garlic to the mushrooms before roasting and think that added another great layer of flavor. I also used baby bellas in place of the cremini mushrooms and again think it contributed to a bolder flavor.
This was good, but I'm not sure it was good enough to justify the 2+ hours it took from the time I started slicing mushrooms to the time the lasagna was on the table.
This was really, really good. I am Italian, and the white sauce on this recipe beats the one for my family recipe hands down. As always, counting the cleaning and cutting, hands on timing adds up to almost one hour and a half, but honestly it's worth it. Word of caution: it was four of us, and we finished the whole 8 servings in one meal. People took seconds and thirds. It was THAT good. Then again, we only had that and dessert on our menu.