How to Bake Duplex Cookies: Irresistibly Delicious Treats!

Ingredients

• 1 cup (226 g) unsalted butter, softened
• 1 cup (200 g) granulated sugar
• 1 large egg
• 2 teaspoons vanilla extract
• 2 ½ cups (312 g) all-purpose flour
• 1 teaspoon baking powder
• 1/2 teaspoon salt
• 1 teaspoon vanilla extract
• 2 cups (240 g) all-purpose flour
• 2/3 cup (65 g) unsweetened cocoa powder
• 1 cup (120 g) powdered sugar
• 1/4 cup (60 g) unsalted butter, softened
• 1-2 tablespoons milk (as needed for consistency)