Like your desserts to be doubly sinful? Then swing by Manhattan’s Flex ­Mussels seafood restaurant and, in lieu of a menu, request the evening’s “DD.” The abbreviation stands for Drunken Donuts, a creation of executive pastry chef (and Top Chef: Just Desserts alum) Zac Young. DDs are deep-fried balls of doughy sweetness served warm and oozing with a cocktail-flavored custard — such as absinthe chocolate or Maker’s Mark caramel — that changes nightly. And since every DD contains about an ounce of booze, don’t forget your ID. $9 for an order of four, 154 W. 13th St. and 174 E. 82nd St.,