Peanut Butter and Banana Whoopie Pies

1½ cups all-purpose flour

1 teaspoon baking soda

1 teaspoon baking powder

frac14; teaspoon salt

frac12; cup creamy peanut butter

frac14; cup (frac12; stick) butter, softened

frac12; cup firmly packed brown sugar

2 eggs

frac12; teaspoon vanilla extract

frac34; cup buttermilk

Filling

1 package (8 ounces) cream cheese, softened

frac14; cup (frac12; stick) butter, softened

2 ripe bananas, peeled and mashed

4 cups confectioners' sugar

Heat oven to 350 degrees. Lightly coat whoopie pie pan with nonstick cooking spray.