Makes 3-4 dozen cookies
Basic Icebox Cookie Dough
Using electric beaters or in a stand mixer fitted with the paddle attachment, beat the butter until smooth. Add the icing sugar and start on low speed to work it in, and then increase the speed to medium-high beating until fluffy, about 2 minutes. Beat in the egg and vanilla. Add the flour, cocoa powder and salt and beat until the dough comes together. Shape the dough into 2 discs and chill until ready to roll.
Preheat the oven to 325ºF (160ºC) and line 2 baking trays with parchment paper.
Lightly knead the dough on a lightly floured surface to soften it a little, making it easier to roll without cracking. Roll the dough out to about ¼-inch (6 mm) thick. Use cookie cutter to cut out desired shapes and place them on a baking tray, leaving an inch (2.5 cm) between them. The dough can be re-rolled until it has been used up.
Bake the cookies for 12-14 minutes, until they lose their shine. Allow the cookies to cool on the trays before decorating.
For the royal icing, beat the meringue powder, icing sugar and warm water with electric beaters or in a stand mixer with the paddle attachment until peaks form (approximately 10 minutes). If not using the icing immediately, cover the surface of the icing with plastic wrap.
Spoon the royal icing into a piping bag fitted with a small plain tip. Pipe the icing onto the cookies and sprinkle with decorator’s sugar and/or add dragées. Allow the cookies to air-dry for at least 2 hours before storing in an airtight container.
The cookies will keep up to a week.