Christmas Tree Sugar Cookies

1. In a large bowl, combine the flour and salt together. Add the lime zest (save the juice for next step). Set aside.
2. In a stand mixer (you can also use the hand mixer for this) add in the butter, sugar, and lime juice and beat it at medium speed, scraping down the sides for at least 2-3 minutes or until the mixture is creamy.
3. Add in the eggs and beat until everything is incorporated well.
4. Add the flour mixture to the butter mixture in batches and mix till the dough is formed (the dough should pull away from the sides of the bowl).
5. Flatten the dough to form a disc and wrap it with plastic wrap. Refrigerate for at least an hour.
6. Preheat the oven to 350 degrees F. Line a cookie sheet with with parchment paper and set aside.
7. Once the dough is chilled, roll out the dough on a lightly floured surface to 1/4-inch thickness and cut out Christmas tree shapes with a 3-inch cookie cutter.
8. Place the cut-out cookies on the parchment paper lined cookie sett. Bake for 12-14 minutes in a preheated oven.
9. Let the cookies cool for 5 minutes on the cookie sheet before transferring them to a wire rack to cool completely.

ROYAL ICING:

1. Add the egg whites to a (clean and dry) stand mixer fitted with a whisk attachment and beat on high until it foams up.
2. Lower the speed and add the sugar in batches and beat until the mixture becomes thick and starts to hold peaks.
3. Divide the icing into 2 parts. Leave one part as it is (white) and tint the other part with pink gel food color until you get desired shade.
4. Reserve 1/4th of both the icing and add 1-2 teaspoons of water to the remaining icing to make them a little thin.
5. We will use thick icing to make the border around the cookies (Because it's thicker and no water has been added it will hold its shape well). The thinner icing will be used to cover the cookies completely.
6. Put all the icings in different icing bags.
7. Outline the cookies with the thick icing first, keeping a little space on the edges of the cookies. Then flood the cookies with the thinner icing; use a toothpick to spread the icing so it’s evenly filled. 
8. While the icing is still wet, sprinkle superfine sugar on top and let it set slightly. Immediately decorate the cookies with different sprinkles (sugar pearls and sugar sprinkles) while the icing is still slightly wet.
9. Serve and enjoy.