Preheat oven to 350℉ (180℃)
Prepare 2 baking sheets by lining with parchment paper or silicone baking mats.
In a medium bowl, whisk together flour, baking soda, salt and lime zest. Set aside for later.
2 Cups All Purpose Flour, ½ teaspoon baking soda, 1 teaspoon Salt, 2 Tablespoons Lime Zest
Using a stand-mixer with the paddle attachment, begin mixing butter and granulated sugar until light and fluffy (approximately 2 - 4 minutes on medium speed). Using a rubber spatula scrape down sides of bowl as needed. Note: a hand mixer may also be used.
½ Cup Unsalted butter, 1 Cup Granulated Sugar
Add egg and lime juice to mixing bowl. Mix on low speed until incorporated. Scrape down sides of bowl as needed.
1 Large Egg, 2 Tablespoons Lime Juice
Add the flour mixture and mix on low speed until combined. Scrape down sides of the bowl as needed.
Create 12 flat discs of cookie dough. Discs should be approximately 1" in diameter and ⅛ of an inch thick.
Scoop the remaining dough onto prepared baking sheets using a cookie scooper (1½ tablespoons per cookie). Leave approximately 2 inches of space between each cookie.
Using the back of a tablespoon or a dough tamper, make an indentation in each cookie. Remove lime discs from freezer.
Place a disc in the center of each cookie. Place the 12 discs of cookie dough over the lime filling. Roll each cookie to seal the disc inside.
Optional. Roll cookies in graham cracker crumbs and place back on cookie sheets.
1 cup Graham cracker crumbs
Bake cookies for 14 - 16 minutes or until the tops are a pale golden color.
Let cookies cool on the baking sheets for 5 to 10 minutes, then transfer cookies to a wire rack to cool completely.