In a large mixing bowl, cream together 225 grams of softened unsalted butter and 200 grams of granulated sugar until light and fluffy (2-3 minutes).

Add 1 large egg and 2 teaspoons of pure vanilla extract, mixing until smooth (about 1 minute).

In a separate bowl, whisk together 375 grams of all-purpose flour, 0.5 teaspoon of baking powder, and 0.25 teaspoon of fine salt.

Gradually add dry ingredients to wet mixture, mixing on low speed until just combined.

Divide the dough into two pieces, flatten into disks, and wrap tightly in cling film. Chill for at least 1 hour.

Preheat oven to 175°C (350°F). Roll out dough to about 6 millimeters thick and cut with cookie cutters.

Bake cut cookies on parchment-lined trays for 9-11 minutes until edges are just golden.

Allow cookies to cool for 5 minutes on the tray before transferring to wire racks.

In a stand mixer, combine 4 tablespoons of meringue powder, 480 grams of icing sugar, and 6-8 tablespoons of warm water. Beat until stiff peaks form.

Outline and flood cooled cookies with royal icing using a piping bag. Let set for at least 8 hours before adding additional decorations.