Banana Whoopie Pies

INGREDIENTS

• 2 cups all-purpose flour
• 1/2 teaspoon baking powder
• 1/2 teaspoon baking soda
• 1/2 teaspoon salt
• 1/2 cup mashed banana (from 1 large ripe banana)
• 1/2 cup sour cream
• 4 ounces (1 stick) unsalted butter, softened
• 1/2 cup granulated sugar
• 1/2 cup packed light-brown sugar
• 1 large egg
• 1 teaspoon pure vanilla extract
• 16 ounces cream cheese, softened
• 1 cup confectioners' sugar, plus more for dusting