Classic Whoopie Cookies Pennsylvania Dutch Delight

Ingredients

• 2 cups (250g) all-purpose flour, plus more for dusting
• ¾ cup (75g) unsweetened cocoa powder
• 1 ½ teaspoons baking soda
• ½ teaspoon baking powder
• ½ teaspoon salt
• ¾ cup (170g) unsalted butter, softened
• 1 ½ cups (300g) granulated sugar
• 2 large eggs
• 1 teaspoon vanilla extract
• 1 cup (240ml) buttermilk
• ½ cup (120ml) hot coffee, brewed strong
• 1 cup (225g) unsalted butter, softened
• 4 cups (480g) powdered sugar, sifted
• 2-4 tablespoons (30-60ml) milk or heavy cream, more or less as needed