Jamie Cantor started her L.A. baking company after working for two years at the French Laundry in Napa. Her new retail space opens this month, but long-standing private and commercial clients know all about her custom-shaped iced sugar cookies, caramel-and-nut-topped brownies, bite-size lemon meringue grahams, baby pots de crème, and, well, the list goes on. Cantor’s creations, many of which are lilliputian versions of favorite hits, are the work of a sophisticated talent in the service of simple pleasures.