Mocha-Walnut Cupcakes With Dulce De Leche Frosting Recipe

Unsweetened chocolate, bittersweet chocolate, and instant espresso powder give these cupcakes a deep, rich flavor that is complemented perfectly by the dulce de leche frosting. Dulche de leche is a caramel flavor widely used in Latin American cuisine. Both the cupcakes and the frosting can be made a couple of days in advance and assembled shortly before serving.  Adapted from "Intensely Chocolate" by Carole Bloom