Preheat the oven to 325°F (160°C) and line a large baking sheet with parchment paper.
In a medium bowl, use clean hands to massage the lemon zest into the granulated sugar until there are no white patches left.
In a large bowl, sift the almond flour and whisk in the lemon sugar.
In another large bowl, add the egg whites and salt. Whip with an electric mixer on high until stiff peaks form (2-5 minutes). Be careful not to over whip your egg whites as they may start to clump.
Using a silicone spatula, fold in the almond extract, limoncello, and ⅓ of the almond flour mixture until combined.
Fold in another ⅓ of the almond flour then add the remaining ⅓, folding until fully combined. The batter will resemble a thick paste.
For rolling, add the granulated sugar and powdered sugar into two separate shallow bowls.
Use a 1 ½ tbsp cookie scoop to scoop out the dough.
Roll each cookie into the granulated sugar then roll into a ball with your hands.
Roll in the powdered until completely coated. Roll into a ball with your hands again to create a uniform shape.* Place on the prepared baking sheet about 1 ½-2 inches (4-5 cm) apart.
Gently press on the tops of the cookies just until cracks form on the edges. You're barely going to press down. This step helps to form better cracks when baking, but you want to avoid flattening them.
Bake for 22-25 minutes or until the cracks are set (they should not be gooey) and the bottoms are golden brown.
Transfer the cookies to a wire rack to cool completely.