To make the sugar cookies:

1. Beat the butter in the bowl of a stand mixer until smooth.
2. Add the sugar and continue beating until thoroughly combined. Add the egg and vanilla extract and repeat.
3. Scrape down the sides of the bowl and add the flour one cup at a time, mixing between each new addition.
4. The dough should be firm, easily peels away from the bowl and no longer sticky.
5. Flatten the dough into a disc, wrap in plastic wrap and chill in the refrigerator for at least 1 hour.
6. Once the dough is chilled, knead it on a lightly floured surface until malleable.
7. Roll the dough out to 1/4″ thick. Cut out with a candy corn shaped cookie cutter.
8. Bake the dough at 350F for 6-10 minutes, depending on the size of the cookies.
9. The cookies are done when they’re no longer shiny on top.
10. In the bowl of a stand mixer, combine the meringue powder/powdered egg whites and lukewarm water.
11. Use a whip attachment to whip the mixture on high until frothy. Scrap down the sides as you go to make sure there’s no residual powder.
12. Sift the powdered sugar and add it to bowl. Continue whipping the icing, this time on medium speed. Stop the machine every 2-3 minutes to spray and scrape down the sides.
13. If you’re adding additional flavoring to your royal icing, you can add it during one of the stops to scrape down the sides of the bowl.
14. Whip the royal icing until you’ve reached a 20-second consistency.
15. Divide the icing into three equal portions and a fourth small portion of just a few tablespoons.
16. Tint the larger portions orange, green and purple, and the small portion black.
17. Using a food-only brush, paint a thin layer of the black icing onto the cookie.
18. Load a small amount of each color into piping bags. Clip a small hole in the tip, and pipe the outline for the features of the jack-o-lantern faces.
19. Load the remaining icing into the bags, and fill in the bottom half of the cookies, leaving inside of the features open for the black icing to show through.
20. Once the outside of the icing has set (about 30 minutes), go back in with the bags you used to pipe the features to add lines from the top of the jack-o-lanterns to the bottom. Allow the cookies to set overnight, or at least 8 hours.
21. Take the remaining icing and pipe a line of it at the top of the jack-o-lanterns. This doesn't have to be perfect.
22. Dip the icing into the sprinkles.
23. Use the remaining black icing to pipe a thin black handle.