In a bowl, combine flour, baking powder, and salt, then mix until well combined. Set aside.
Add the butter to the mixing bowl, use the paddle attachment of the standing mixer (or use a handheld mixer). On medium speed, cream the butter for a minute or until fluffy. Lower the speed and slowly add the sugar. Bring the speed to high and mix for 2 minutes. Turn off the machine and scrape the sides. Bring the speed to low and add the egg yolk one at a time, mix until all incorporated.
Bring the speed back up to high and mix for 2 minutes or until fluffy and light in color. Lower the speed and slowly add the flour mixture, stop the mixer and scrape the sides of the bowl. Add lemon juice, lemon, zest, and vanilla, bring the speed to medium-high and mix until the dough comes together.
Remove the dough from the mixing bowl and form it into a log. Wrap in plastic wrap and chill for 30 minutes to an hour.
Line a baking sheet pan with parchment paper. Lightly dust a surface and roll the chilled dough. If the dough is too hard, let it sit on top of the counter and bring it down to room temperature or until pliable. Cut the cookie dough into any shape you like. Option: sprinkle crystal sugar on top.
Preheat the oven to 350ºF. Arrange the cut-up cookie dough onto a prepared baking sheet pan, line them at least 2 inches apart (the dough expands when baking). Freeze for at least an hour before baking (if the baking pan doesn’t fit in your freezer, place them on a plate and freeze, then transfer onto a baking sheet pan lined with parchment paper when ready to bake).
Bake for 15-18 minutes or until the edges are golden brown. Cool on cooking for an hour.