Mix the butter and sugar in a stand mixer fitted with a paddle attachment at medium speed until they are well combined and creamy.

Add the egg and vanilla and combine.

Whisk the flour, salt, and baking powder together in a separate bowl.

Add the flour mixture to the wet ingredients little by little. Mix at low speed until well combined. Make sure you scrape the sides of the bowl so it is all mixed in.

Roll the dough into a sheet that is 1/4” inch thick. Place it on a sheet of parchment paper or an acrylic sheet.

Place the dough in the refrigerator for 30 minutes.

Preheat the oven to 350 degrees. Add some parchment paper onto your baking sheet and set aside.

Cut the cookie shapes and place them on a baking sheet.

Bake for 15 to 20 minutes, or until the edges are golden.

Let them cool for at least an hour.

Mix your confectioners’ sugar, meringue powder, 3 tablespoons of water, and desired flavor of extract with a standing mixer using a whisk attachment. Beat the icing ingredients together on high speed for about 2 minutes.

Place a spoon or knife into the icing, and lift it up. It should drizzle down and smooth out in about 5 - 8 seconds. If it looks too thick, add a bit more water little by little because it could easily get too thin. If it's too thin, add a bit more confectioner’s sugar. The icing should be about a flooding consistency.

Separate the frosting into three bowls and using a toothpick, add a drop of coloring onto each and swirl it on the white icing. If you use two colors, repeat the same with another color in that bowl. You will notice the first color in this case, I used green, and as you swirl you will notice different shades across the icing. Continue by adding your second color onto the toothpick, in this case red, and do the same. Swirl it around the icing.

Keep in mind that the icing will harden quickly, so make sure to cover anything not being used right away.

Dip the whole top of the cookie in the royal icing mixture. Make sure all of the edges are covered. Lift the cookie carefully and let the extra icing drip off the cookie by holding it over the bowl. Place it on a cooling rack to set, but keep in mind some of the icing might drip a bit.

Repeat the process for all of the cookies in all of the icing colors you have chosen to use until you have finished them all.

Let the cookies sit until the frosting has set for about 2 hours.