Prepare Dry Ingredients: Sift together powdered sugar, almond flour, egg white powder, and cocoa powder into a large mixing bowl. Set aside.

Make Meringue: Beat egg whites on medium speed until frothy. Gradually add granulated sugar, then increase speed until stiff peaks form, about 5-7 minutes.

Combine: Gently fold meringue into sifted dry ingredients. Ensure batter is well combined and flows smoothly.

Pipe Shells: Pipe batter into small circles on prepared baking sheets. Allow to sit for 20 minutes until a skin forms.

Bake: Preheat oven to 300°F (150°C) and bake macarons for approximately 12 minutes. Let them cool completely.

Prepare Buttercream: Whisk together marshmallow cream, butter, and vanilla until smooth. Gradually mix in powdered sugar and heavy cream.

Assemble: Dip tops of shells in melted chocolate, decorate with marshmallows and sprinkles. Pipe buttercream on half of the shells and sandwich with the tops.