The promotional posters for Joël Robuchon at the Mansion (702.891.7925, www.mgmgrand.com), one of two restaurants the French chef opened at the MGM Grand last October, are overwrought even by Las Vegas standards. On a backdrop of black above a ribbon of royal purple, gold letters proclaim, “Every meal you’ve ever eaten was simply in preparation for this moment.” Still, it is difficult to fault MGM Grand’s enthusiasm. Robuchon retired at the peak of his powers in 1996 but returned to the dining scene in 2003 with L’Atelier du Joël Robuchon, a relatively casual restaurant that has locations in Paris and Tokyo, at the MGM Grand in Las Vegas (702.891.7358), and soon, in New York. However, Joël Robuchon at the Mansion, with its elegant white facade and 17-course tasting menu, is his first formal restaurant since his retirement. Be prepared for an authentic taste of Paris amid the casinos.