1cupconfectioners' sugar, plus 2 more cups for rolling
1/4cupfreshly squeezed lemon juice
1heaping tablespoonlemon zest
Preheat the oven to 350 degrees. Line two baking sheets with parchment paper.
In a small bowl, whisk flour, baking powder and salt; set aside. In the bowl of a stand mixer fitted with the paddle attachment, cream the butter and 1 cup of the sugar until light and fluffy, about 3 minutes. On low speed, mix in the egg yolk, lemon juice, zest and vanilla until incorporated. Add the dry ingredients, mixing on low speed just until combined. If the dough is crumbly, use your hands to kneed the dough gently until it comes together and forms a ball. Roll the dough into 1" sized balls and place 1" apart on the prepared baking sheets. Bake for 18 to 20 minutes, or until lightly golden brown.
Remove from oven and allow to cool slightly. While the cookies are still warm, roll them in the remaining 2 cups confectioners' sugar and place on a wire baking rack to cool completely. Store in an airtight container for up to 2 weeks.