In a bowl whisk together the flour, the baking powder and a pinch of salt. In another bowl with an electric mixer cream together the brown sugar, the peanut butter, and the butter and beat in the
egg and the vanilla. Beat in the flour mixture alternately with the milk, beating well after each addition, and stir in 1/2 cup of the chocolate chips. Divide the batter among 12 paper-lined 1/2-cup muffin tins and bake the cupcakes in the middle of a preheated 350 F oven for 20 to 25 minutes, or until a tester comes out clean. Turn the cupcakes out onto a rack and let them cool completely.
In another bowl combine the remaining 3/4 cup chocolate chips and the cream, scalded, let the chips soften, and whisk the mixture until it is smooth. Let the icing cool completely, whisk it until it is fluffy, and spread it on the cupcakes.
Recipe courtesy of Gourmet Magazine