Zest one lemon and add to a small bowl with ½ cup of granulated sugar. Using your fingertips, rub the lemon and sugar together for one minute. Set bowl aside (this is used later to roll cookies in after scooping and before baking).
1 Tablespoon Lemon Zest, ½ Cup Granulated Sugar
Make Cookies
Prepare 2 baking sheets by lining with parchment paper or silicone baking mats.
In a medium bowl, whisk together flour, baking soda, salt and lemon zest. Set aside for later.
2 Cups All Purpose Flour, ½ teaspoon baking soda, 1 teaspoon Salt, 2 Tablespoons Lemon Zest
Using a stand-mixer with the paddle attachment, begin mixing the butter and granulated sugar until light and fluffy (approximately 2 - 4 minutes on medium speed). Scrape down sides of bowl as needed. Note: a hand-mixer may be used.
½ Cup Butter, 1 Cup Granulated Sugar
Add egg and lemon juice. Mix on medium speed until well incorporated. Scrape down sides of bowl as needed.
1 Large Egg, 2 Tablespoons Lemon Juice
Add the flour mixture and mix on low speed until combined.
Using a small cookie scooper create balls of dough (approximately 1½ tablespoons per cookie). Roll the dough in the lemon sugar (optional).
Place the cookies onto the parchment-lined baking sheets. Leave approximately 2 inches of space between each cookie.
Using your thumb or the back of a teaspoon, press into the middle of each cookie to make a well.
Bake cookies for 10 - 12 minutes or until the tops are a pale golden color.
Let cookies cool on the baking sheets for 5 to 10 minutes, then transfer them to a wire rack to cool completely (note: if the 'cookie well' has minimized, press lightly again with your thumb or the back of a teaspoon to make the well larger).
Spoon lemon curd into the well of each cookie.
½ Batch Lemon Curd
Notes
Storage: keep cookies in an airtight container in the refrigerator for up to 3 days (the curd is perishable and should be kept cold).