1. For the dough add the butter and sugar to a large bowl and mix until light and fluffy – about 4-5 minutes. Add the egg and vanilla extract and mix until well combined. Mix the flour with cocoa powder, baking powder, cinnamon, and salt and add to the bowl – mix until just combined. Shape the dough into a ball, flatten it and wrap in plastic wrap. Place in the fridge for at least 2 hours or overnight.

 

2. Preheat the oven to 325°F (165°C). Line a baking sheet with baking parchment and set aside. Take about half of the dough and roll out on a floured surface – about 0.2 inches thick. Use “Day of the Dead” cookie cutters and cut out as many cookies as possible and place them on the prepared baking sheet. Roll out more dough and cut more cookies if there is still room on the baking sheet – if not, place leftover dough and already cut out cookies in the fridge for the next round. Bake the first batch of cookies for about 10-12 minutes. They should be firm but not dry or hard. Take out of the oven and let cool down on the baking sheet for some time, then transfer to a wire rack and let cool down completely. Repeat with the remaining dough until all dough is used.

 

3. For the royal icing add 3 1/2 cups of the confectioners’ sugar and the cream of tartar to a large bowl and mix until well combined. Add the egg whites and lemon juice and mix until you get a smooth and shiny icing. It should be thick, but runny enough to pour. Adjust with confectioners’ sugar or egg white if the icing is too liquid or too thick. Fill about 1/4 of the icing into a piping bag with a small round tip. Outline the cookies with the icing and let dry for about 5-10 minutes. Use the same icing (maybe with a larger round tip) to flood the cookies with icing within the outlines. Use a small spatula to smooth out the top and push the icing into all corners of the outlines. If the icing is too thick for the flooding, mix in some more egg white and/or lemon juice to get a slightly runnier icing. Let dry for at least 8 hours. Keep the remaining icing in an airtight container.

 

4. When the cookies are dry divide the icing into 5-6 equal portions and color each with some food coloring (keep some white just in case if you need it later). Fill into piping bags and decorate the cookies to your liking. Let dry completely (at least 2 hours) and store in an airtight container in a cool place.