Sift Dry Ingredients: In a medium bowl, sift together the flour, baking powder, and kosher salt. Sifting aerates the flour and prevents salty clumps.

Cream Butter: In a stand mixer fitted with the paddle attachment, beat the butter on medium speed for about 2 minutes until smooth and velvety.

Aerate with Sugar: Add the sugar to the butter. Beat for about 3 minutes until the mixture is pale, light, and fluffy.

Add Wet Ingredients: Add the eggs one at a time, beating well after each. Pour in the vanilla extract and mix briefly.

Combine: Turn the mixer to low. Add the sifted dry ingredients. Beat just until combined. Stop mixing as soon as the white streaks of flour disappear to avoid tough cookies.

Shape and Chill: Divide dough in half. Shape into smooth logs on a lightly floured surface. Wrap securely in plastic wrap and refrigerate for at least 1 hour (or up to a week).

Coat and Slice: Remove logs from fridge. Unwrap and roll in sprinkles (if using). Slice into 1/4-inch thick rounds using a sharp knife.

The Freezer Trick: Preheat oven to 350ºF (175ºC). Arrange cookies on parchment-lined baking sheets. Place the baking sheets in the freezer for 10 minutes.

Bake and Cool: Bake for 12 to 15 minutes until set (dry on top, slightly golden edges). Cool on the sheet for 5 minutes, then transfer to a wire rack.