1 3/4 cups powdered sugar, plus 1 1/2 cups for garnish
1 large egg yolk
1 tablespoon grated lemon zest
1/3 cup fresh lemon juice
1 teaspoon vanilla bean paste
3 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon kosher salt
Preheat the oven to 350°F. Line 2 baking sheets with parchment paper.
In a stand mixer fitted with a paddle attachment, cream the butter and 1 3/4 cups powdered sugar starting on low speed and gradually increasing to medium-high speed for about 2 minutes. Turn off the mixer and scrape down the sides and bottom of the bowl with a spatula. On a low speed, slowly add the egg yolk, lemon zest, lemon juice, and vanilla bean paste, and mix until incorporated, about 2 minutes.
In a medium bowl, whisk together the flour, baking powder, and salt, then slowly add that to the lemon mixture. Mix on medium speed until just combined or until a dough forms, about 1 minute.
Use a 1 1/2-tablespoon scoop to portion the dough and place on the prepared baking sheets, spacing the scoops about 1 inch apart.
Bake until the cookies are still very blonde in color, but the bottoms are golden, about 15 minutes. Let the cookies cool on the baking sheets for 10 minutes.
Place the remaining 1 1/2 cups powdered sugar in a medium bowl. Roll the cookies in powdered sugar until completely coated, then let cool on a cooling rack for another 15 minutes.
Store leftovers in an airtight container, at room temperature, for up to 5 days.