Begin by creaming together 1 cup of softened butter and 1 cup of white sugar until fluffy, about 3 to 5 minutes. Beat in 1 large egg and 1 teaspoon of vanilla extract until well combined. In a separate bowl, whisk together 3 cups of all-purpose flour, 1 teaspoon of baking soda, and 1 teaspoon of baking powder before gradually adding to the butter mixture. Chill for at least 1 hour.

Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper. Roll out the chilled dough to about ¼-inch thickness. Use a cookie cutter to cut out shapes and carve a wedge-shaped cavity into each cookie.

Bake the cookies for 10-12 minutes or until lightly golden. Let them cool completely on a wire rack to prevent icing from melting.

Prepare royal icing by whisking together 4 cups of powdered sugar, 2 tablespoons of milk, and 1 teaspoon of vanilla until thick yet smooth. Adjust with more milk or sugar if needed.

Once cookies are cool, fill cavities with royal icing and press rock candy crystals into the icing. Add edible glitter dust for sparkle. Let sit for 2 hours to set before serving.