01 -
In a large bowl, whisk together all-purpose flour, baking powder, baking soda, and salt to ensure even distribution.
02 -
In another large bowl, using an electric mixer, beat unsalted butter, granulated sugar, lemon zest, and vanilla extract for 2 minutes until mixture is pale and fluffy. Beat in the egg until evenly incorporated, then mix in sour cream.
03 -
Gradually fold the dry ingredients into the wet mixture using a spatula until combined. Transfer the sticky dough onto plastic wrap, flour your hands, and shape into a 10–12 inch log. Wrap tightly and refrigerate for 2 hours.
04 -
Preheat oven to 375°F. Line two large cookie sheets with parchment paper. (Note: Temperature will be lowered to 350°F during baking.)
05 -
Slice the chilled dough log into 18 equal portions. Roll each portion into smooth balls, and coat evenly by rolling first in granulated sugar, then in powdered sugar. Place dough balls on cookie sheets, ensuring at least 3 inches of spacing.
06 -
Using a round ½-teaspoon measuring spoon, carefully press an indentation into the center of each dough ball. Gently reshape any cracks. Fill each indentation with a heaped teaspoon of lemon curd.
07 -
Bake in preheated oven at 375°F for 3 minutes, then lower temperature to 350°F and continue baking for 10 minutes, until cookies are cracked and golden, and lemon curd appears matte.
08 -
Let cookies cool on baking sheets for 2 minutes before carefully transferring to a wire rack to cool completely. Once cooled, dust with icing sugar and serve.