Mrs. Weasley's Ugly Christmas Jumper Cookies Will Leave You in Stitches

Mrs. Weasley's Ugly Christmas Jumper Cookies

Adapted from Alton Brown [1] and Nicole Perry, POPSUGAR Food

Use a #2 or #3 icing tip.

1 batch sugar cookie dough [2]
1 pound powdered sugar
2 large egg whites
Red, blue, and black gel food coloring

Preheat oven to 375°F. Line two half-sheet pans with parchment paper or Silpats.
Roll out cookie dough to 1/4-inch thick. Use a jumper cookie cutter to cut out the dough. Place the cookie-dough rounds at least 1 inch apart on the half-sheet pan, and bake for 8 to 10 minutes, or until cookies are just beginning to turn brown around the edges, rotating cookie sheet halfway through baking time. Let sit on baking sheet for 2 minutes, and then transfer to a wire rack to let them cool completely.
While the cookies cool, combine the powdered sugar and egg whites in the bowl of a stand mixer. Mix on low speed until completely blended and the icing holds a ribbon-like trail on the surface of the mixture for 5 seconds when you raise the paddle. If it's too thick, then add water 1 teaspoon at a time; if it's too thin, then add powdered sugar 1 tablespoon at a time until it reaches the desired thickness. Divide the icing and dye to your liking, then transfer to piping bags fitted with round tips.
To decorate, pipe or spread a thin layer of the royal icing on a cookie. Allow the icing to dry and harden completely before piping on lettering and jumper details. Let dry completely before storing or stacking the cookies.