In a medium mixing bowl, whisk together flour, baking powder and salt. Set aside.
2 cups all-purpose flour, ½ teaspoon baking powder, ½ teaspoon kosher salt
In another bowl, using a hand mixer, cream butter and sugar together until smooth.
¾ cup unsalted butter, ¾ cup granulated sugar
Add the egg yolks, vanilla, lemon juice, and lemon zest and whisk until smooth and combined.
2 egg yolks, 1 teaspoon pure vanilla extract, 1 lemon
Add the dry ingredients to the wet ingredients in 2 batches, whisking just until combined after each addition.
Chill the batter in the fridge for 2 hours.
Preheat oven to 350°F and line a large baking sheet with parchment paper.
Roll 1-tablespoon-sized balls of batter and place them onto the prepared tray 2 inches apart. Flatten the balls slightly if you desired flatter cookies.
Bake for about 10-12 minutes, until the edges are beginning to turn golden.
When done, cool on a wire rack to room temperature.