By Cathy Branciaroli, Food Correspondent, The Times The Mole Chicken at recently opened La Pina Restaurant marries a hint of chocolate sweetness with a spicy back-bite of flavor. While we usually think of dishes made with chocolate as sweet, sometimes decadent candies, beverages or desserts, chocolate in Mexican foods can be a spicy ingredient that enlivens sauces and savory dishes.  There’s a...