Chocolate Peppermint Whoopie Pies with Marshmallow Filling - My Homemade Recipe

Ingredients

• 2 cups all-purpose flour.
• 1/2 cup cocoa powder.
• 1 teaspoon baking soda.
• 3/4 teaspoon salt.
• 1/2 cup unsalted butter, at room temperature.
• 1 cup packed brown sugar.
• 1 large egg, at room temperature.
• 1 teaspoon vanilla extract.
• 1 cup buttermilk, at room temperature.
• 3/4 cup unsalted butter, at room temperature (for filling).
• 1 1/4 cups confectioners' sugar, sifted.
• 1 teaspoon vanilla extract (for filling).
• 1/2 teaspoon peppermint extract.
• 1/8 teaspoon salt (for filling).
• 2 1/2 cups marshmallow crème.
• Crushed candy canes, for garnish.