Peppermint Whoopie Pies

2 cups flour

frac12; cup cocoa powder

1 teaspoon baking powder

1 teaspoon baking soda

1 teaspoon salt

frac12; cup (1 stick) butter

1 cup brown sugar, packed

1 egg

1 teaspoon pure vanilla extract

frac12; teaspoon peppermint extract

1 cup buttermilk

Filling

frac12; cup (1 stick) butter, softened

1 jar (7.5 ounces) marshmallow creme

2 teaspoons pure vanilla extract

1frac14; cups confectioners' sugar

1 cup crushed peppermint candies (about 50 peppermint discs)

Heat oven to 350 degrees.