Mix together the flour, salt and baking powder in a bowl.
In a separate bowl, cream the butter and sugar with an electric mixer until it becomes light and fluffy. Add the milk, egg and vanilla and mix well.
Slowly add the dry ingredients and mix until just combined.
Shape the dough into a ball, wrap in plastic wrap and chill in the fridge for 1 hour.
Roll the dough on a floured surface until ¼-inch thick. Use a sharp knife to cut out the cookies and place them on a baking sheet lined with parchment paper.
Bake the cookies at 350F for 10 minutes, until the edges are just starting to brown. Cool completely.
Make the royal icing:
Pour the warm water into a large bowl. Add the meringue powder and whisk for a couple seconds until frothy. Add the cream of tartar and whisk again.
Add the powdered sugar all at once and using an electric mixer, mix on low speed for 10 minutes. The icing should stay on the surface for 5-7 seconds when drizzled. Add the vanilla extract and mix well.
Dye 1/3 cup of icing red. Divide the icing into 2 bowls. Leave one bowl white and dye the other bowl black.
Place the icing into piping bags fitted with small, round piping tips.
Decorate:
Use a bottle cap as a guide to draw the outlines of the sunglasses onto the cookies with the edible ink pen.
Use the black icing to draw and fill in the glasses. If you find that the icing is too stiff, add a VERY TINY amount of water to the frosting, then return to the piping bag and start again. Or you can use a toothpick to smooth the icing and remove any lumps. Allow the glasses to dry and harden for about 30-45 minutes before piping anything else. The borders need to be dry enough that neighbouring icing doesn’t bleed into it.
Next, Pipe the black hair and the portion of the white face that is below the glasses. Allow to dry for 45 minutes. Finally, pipe the white forehead and the red lips. Use a toothpick to create the sharp, defined edges of the lips.
Allow the cookies to fully dry, about 1-2 hours. Then enjoy!