Melt the Butter: Begin by melting ½ cup of butter in a saucepan over low heat. Once melted, remove it from heat and allow it to cool to room temperature.

Mix the Sugars and Wet Ingredients: In a large mixing bowl, combine ½ cup granulated sugar and ½ cup dark brown sugar with the cooled butter. Whisk them together until well combined, then add 1 large egg and 1 egg yolk along with 1 teaspoon of vanilla extract.

Combine Dry Ingredients: In a separate bowl, whisk together 1 ½ cups all-purpose flour, ⅔ cup cocoa powder, 1 teaspoon baking powder, ½ teaspoon baking soda, and ¼ teaspoon salt.

Combine Wet and Dry Mixtures: Gradually add the dry ingredient mixture into the wet ingredients. Gently fold the two mixtures together until just combined.

Preheat the Oven and Prepare the Baking Sheet: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

Shape the Cookies: Once chilled, scoop out tablespoon-sized portions of the dough and roll them into balls, slightly flattening each ball.

Bake the Cookies: Place the baking sheet in the preheated oven and bake for 9-10 minutes.

Prepare the Buttercream Frosting: In a bowl, mix ½ cup softened butter, 2 cups powdered sugar, 1 teaspoon vanilla extract, and a splash of milk. Beat until the frosting is smooth.

Decorate the Cookies: Once the cookies are cool, use a piping bag to decorate the top of each cookie with the buttercream, mimicking mummy wraps.