1/4 cup + 1 teaspoon warm water, plus more to thin
In a medium bowl, whisk together the flour, cocoa powder and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat together the butter and sugar on medium speed until well blended, about one minute (don’t over-mix or else your cookies won’t hold their shape when baked). Stop the mixer and scrape down the sides of the bowl with a rubber spatula. Add the egg and the vanilla and beat on medium speed just until combined.
With the mixer running on low speed, add the flour mixture all at once and mix until just combined. Stop the mixer and scrape down the sides and bottom of the bowl, then mix again on low speed until the dry ingredients are blended in. Try not to over-mix the dough.
Divide the dough into two balls and place each one on a piece of parchment paper. Pat with the palm of your hand to flatten slightly, then place another piece of parchment paper on top. Place two six millimeter rolling sticks on either side of the parchment paper (you can omit the rolling sticks if you don’t have them) and then use a rolling pin to roll out the dough to an even thickness. Repeat with the other ball of dough. Slide the rolled doughs onto the back of a baking sheet and pop in the refrigerator until firm, about 25 minutes.
Preheat the oven to 350°F (180°C) and line three baking sheets with parchment paper.
Remove one sheet of dough from the refrigerator, peel off the top piece of parchment paper and use a cookie cutter to cut out desired shapes. Repeat with the second sheet of dough. Place the cut cookies on the prepared baking sheets, spacing them about five centimeters apart, and pop into the freezer until firm, at least 25 minutes. Gather up the remaining dough and repeat.
Bake the cookies until the edges have set, about 15 to 18 minutes, depending on your oven. Remove the baking sheets from the oven, place them on a wire rack and allow the cookies to cool completely. Cookies will keep in an airtight container for up to three weeks.
For the Royal Icing:
Using a clean paper towel, thoroughly wipe the inside of a stand mixer bowl, as well as the paddle attachment with white vinegar. The acid in the vinegar will remove any greasy residue, which can affect the drying process of the icing.
Place the confectioners’ sugar and meringue powder in the prepared bowl and mix together on low speed until combined. With the mixer running on low speed, add the water until the mixture is moist and mixes easily. If the mixture is a bit too thick, add a little more water. Allow to mix on low speed for ten minutes.
During this time, the mixture will thicken and double in volume and should hold a stiff peak. This is called Stiff Peak icing. The consistency is very thick and is usually used as an edible “glue” (think gingerbread houses) or for piping certain decorations.
With the mixer running on low speed, add more water, a little at a time, until the icing holds soft peaks, similar to the consistency of toothpaste. This is called Soft Peak icing, and is ideal for piping outlines, borders and other details on cookies and cakes.
With the mixer running on low speed, add more water again, a little at a time, until the icing is runny. When drizzled back on itself, the ribbon of icing should disappear within 10-12 seconds, no more, no less. This is called Flood icing, and is used to “flood” or fill in cookies after outlining them in soft peak icing around the edges.
Be sure to keep any icing that you aren’t using covered up with a damp tea towel, as it dries out quickly.
Decorating the Santa cookies:
Make the royal icing and turn it into soft peak consistency. Fit a small pastry bag with a small, plain piping tip (I used a Wilton #2 tip), fill the bag half-full with the royal icing and close with a binder clip. Place one of the cooled cookies on a flat work surface and pipe a border of icing all the way around the cookie, making sure that there are no gaps in your border. Place the cookie back on the baking sheet and repeat with the remaining cookies.
Once all of the cookies have a border, turn the royal icing into flood consistency and fill a squeeze bottle with the icing. Cover the remaining icing with a damp tea towel. Carefully flood each cookie and allow them to dry for at least eight hours or overnight.
Once the icing is completely dry, use a ruler to draw straight lines on each of the cookies using an edible food marker. Use different marker colours to write notes to your hearts content!
Dried cookies will keep for up to three weeks in an airtight container or in sealed cellophane bags.