In a large bowl or the bowl of a stand mixer, beat together the butter, sugar and both zests until light and fluffy. Add the eggs one at a time scraping down the bowl after each addition. Add the vanilla, and mix well. Add the flour, baking powder, and salt, and mix until a firm dough forms.
Place ½ the dough between 2 pieces of plastic wrap and roll out to ¼" thickness. Repeat with the rest of the dough. Chill at least one hour or up to 3 days on a flat cookie sheet
Preheat the oven to 350℉. Cut out desired shape of cookies and bake on a non-stick cookie sheet. Leave at least 2" between each cookie.
Bake 8-10 minutes or until the bottom edges are just slightly golden. Bake one sheet at a time to ensure even cooking. Do not let tops or sides brown.
Let cool on pan 5 minutes then transfer to rack to cool completely.
In a small bowl whisk together the lime juice and ½ cup of the icing sugar until smooth. Add icing sugar a few tablespoons at a time until the desired consistency is reached. Glaze cookie either by drizzling glaze with a fork over the cookies or dunking the tops in the glaze. Let dry on a cooling rack. Add sprinkles if desired.
Recipe by Chateau Elma at https://www.chateauelma.com/citrus-glazed-sugar-cookies