1 pkg (18-1/4 ounces) yellow cake mix
3/4 cup creamy peanut butter
1-1/4 cups water
1/4 cup canola oil
whipped chocolate icing
In a large bowl, combine the cake mix, peanut butter, eggs, water and oil; beat on low speed for 30 seconds. Beat on medium for 2 minutes. Fill 2 dozen paper-lined muffin cups two-thirds full. Bake at 350 deg for 18-22 minutes or until a toothpick inserted near the center comes out clean. Cool for 10 minutes before removing from pans to wire racks to cool completely. Spread each cupcake with a generous layer of icing.
If you are the sort who prefers to make your own icing, here is a great recipe.
2 cups semisweet chocolate chips
1/2 cup heavy whipping cream
1/2 cup butter, softened
1 cup confectioners' sugar
Place chocolate chips in a large bowl. In a small saucepan, bring cream just to a boil. Pour over chocolate; whisk until smooth. Cool, stirring occasionally, to room temperature. Add butter and confectioners' sugar; beat until smooth. Frost cupcakes.