Good Housekeeping's recipe for making whoopie pies, fluffy devil's-food cookies filled with a creamy marshmallow center, is easy to follow. To begin, preheat the oven to 350 degrees, and grease 2 large cookie sheets.
First, prepare the cookie dough. In a large mixing bowl, combine 2 cups flour, 1 cup sugar, 3/4 cup milk, 1/2 cup unsweetened cocoa powder and 6 teaspoons butter or margarine. Also add in 1 teaspoon baking soda, 1 teaspoon vanilla extract, 1/4 teaspoon salt, and 1 large egg. Blend all these ingredients together until smooth. Drop the dough by tablespoon onto the cookie sheets. Each sheet has 12 round cookies. Bake cookies for 12-14 minutes, rotating between the upper and lower racks of the oven, and pull out when cookies are puffy or an inserted toothpick comes out clean. Transfer the cookies to a wire rack to cool completely.
Next, prepare the marshmallow filling. In a large bowl with a mixer at medium speed, beat 6 tablespoons butter or margarine until smooth. Reduce mixer speed to low, and gradually mix in 1 cup confectioners' sugar. Mix in 1 jar marshmallow cream and 1 teaspoon vanilla extract.
Spread 1 tablespoon marshmallow filling on the flat side of 12 cookies. Top with the remaining cookies. This recipe makes 12 servings.