Place the flour, sugar, baking powder and salt into a food processor and pulse about 5-6 times until combined.
Cut the butter into ½” cubes and add to the flour mixture. Pulse 10-15 times until the butter is incorporated and the mixture looks powdery or sandy.
In a small separate bowl, whisk together the whole egg, egg yolk and vanilla. Add the mixture to the food processor and pulse until the dough just begins to come together.
Dump the dough out onto a lightly floured surface and knead 5-6 times to form a smooth dough.
Shape the dough into a square, wrap in plastic wrap and place in the refrigerator for at least 2 hours and up to 2 days.
Preheat your oven to 350℉
After chilling, cut the dough in half and work with one piece at a time.
Roll each piece, between two pieces of parchmnet paper, to a thickness of 3/16”. Cut out as many pieces as you can with the cookie cutter of your choice.
Place the cookies on a parchment lined baking sheet.
Bake the cookies for 11-12 minutes or until the edges begin to turn a light golden brown.
Remove from the oven and let cookies cool on the pan for about 10 minutes. Then, place the cookies on a metal rack to cool completely.