In each installment of Pastry Cases, sweets fanatics and lovers of (most) things baked Charlotte Druckman and Gabriella Gershenson(of Every Day with Rachael Ray) share a favorite confection, slice of cake, ice cream scoop, or other delectable delight worth the sugar high—and the trek. In this week’s edition, the twosome bring a third, Momofuku’s Christina Tosi, and together they sample the elegant Franco-Japanese dainties at Patisserie Tomoko in Williamsburg, Brooklyn.