In a medium bowl, whisk together the flour, baking powder and salt. Set it aside. In a separate bowl, use a hand mixer to beat the butter and sugar together until creamed together. Then add the egg and vanilla and beat until combined, scraping down the sides as needed.

Add the dry ingredients to the wet and mix on low speed until combined. Dough will be thick. Scoop about 2 tbsp. of dough per cookie and roll into balls. Place the dough balls onto a plate, cover with foil or plastic wrap and place in the fridge for a minimum of 2 hours (and up to 4 days).

Once the dough has chilled and you're ready to bake, preheat the oven to 350°F. Line a couple large baking trays with parchment paper or silicone baking mats.arrange the dough balls onto the trays, about 3 inches apart from each other. Bake for 10-12 minutes, or until lightly browned on the edges. The centers should still look very soft. Immediately press a couple of candy corn gently into the tops of each cookie.