Preheat the oven to 300°F. Line a baking sheet with parchment paper.
In a medium bowl, mix together the flour, cornstarch and salt. Set aside.
In a large bowl, cream the room temperature butter and confectioners powdered sugar together until smooth and creamy.
Add in the vanilla extract and beat for 3 minutes. Set a timer and don't skip this step - this will make the cookies light and flakey.
Add in half of the flour mixture and beat with hand mixer.
Add the last half of the flour mixture and blend again.
At this point you might have to use a spatula or your hands to finish mixing.
The dough will stick together nicely and be a little bit crumbly. Place in the refrigerator to chill for 15 minutes.
Remove from fridge and use 1 Tbsp to roll into balls between your hands. Place on the baking sheet.
Use a fork or the bottom of a glass to gently flatten each cookie.
Top the cookies with sprinkles, crushed candy canes or Hershey's kisses (or anything else you'd like). Gently press the candies into the tops of the cookies so that they stick while baking.
Bake for 8 minutes. Remove from the oven and let sit on baking sheet for 10 minutes.
Gently place each cookie on to a rack. They will be delicate while still warm - I like to use a spatula to transfer so they don't break. Let the cookies cool completely on the rack. Cookies with chocolate will take longer to cool - You can place theses cookies in the fridge to help harden the chocolate faster.
Place in an airtight container on counter or in fridge for up to 1 week.These cookies can also be frozen in an airtight container for 3 months.