For the cookie dough:
14 tablespoons unsalted butter, room temperature
1/2 cup powdered sugar
1 tablespoon key lime zest, packed
2 tablespoons fresh key lime juice
1/2 teaspoon coconut extract
1 1/2 cups unbleached all-purpose flour
1/4 cup cornstarch
1/4 teaspoon salt
For the icing:
1 cup powdered sugar (more or less for desired consistency)
1/2 teaspoon coconut extract
2 tablespoons fresh key lime juice (more or less as needed)
1/2 cup sweetened shredded coconut for garnish
1 teaspoon key lime zest for garnish
To make the cookie dough:
In a large mixing bowl, beat the butter on medium speed until creamy. Add 1/2 cup of powdered sugar and beat until light and fluffy. Scrape down the sides of the mixing bowl and blend again until incorporated.
Add 1 tablespoon of lime zest, 2 tablespoons lime juice and 1/2 teaspoon coconut extract. Gently mix on low until incorporated, scraping down sides with a spatula as needed.
In a small mixing bowl, whisk together the flour, cornstarch and salt. Add the flour mixture in four batches to the creamed butter and lime mixture. Blend on medium-low until each addition is incorporated. Scrape the dough into a ball, cover the bowl with plastic wrap and refrigerate for 1 hour.
To bake the cookies, preheat oven to 350F. Line a baking sheet with parchment paper. Scoop a level spoonful of dough using a 1-inch cookie scoop. Roll each into a tight ball and place two inches apart on the prepared baking sheet. Press each dough ball gently with the flat bottom of a small glass or measuring cup to the desired thickness. Bake for 13 minutes at 350F or until lightly browned around the edges. Slide the parchment paper onto a wire rack to cool.
Repeat with a new piece of parchment paper placed on a cooled cookie sheet. Cool cookies completely if planning to top with icing. Alternatively, you can also toss the warm cookies in powdered sugar instead.
To make the icing:
Whisk together 1 cup of powdered sugar, 1/2 teaspoon coconut extract and the remaining 2 tablespoons fresh key lime juice. Add more lime juice or sugar as needed to reach the desired consistency. Spread the icing on the cooled cookies and immediately top with shredded coconut and lime zest. Allow the icing to fully set then store the cookies in a cool location or refrigerate for longer storage.