This here is pretty close: http://www.gourmet.com/recipes/diaryofafoodie/2007/01/beets_in_salt_crust
Just one hour, not two, or rather until more or less done. Use something very thin, like a cake tester, to check the doneness. Otherwise you might break the crust. Then turn off the oven, open the door and let it sit in there for another hour. Serve with beurre noisette to which you add quite a bit lemon juice. You may add herbs to the beurre to your taste like chervil or chives. Balsamic is optional, too, but it tastes good with it. Use beets with about 150g weight and, if possible, not too many blemishes. Alain Passard doesn't use egg white in his recipe, but I figure it's easier that way to cover the beets with it.