Increase oven temp to 375F.
Sift flour, salt, cornstarch into a medium bowl. Give it a whisk.
In a standing mixer fitted with a paddle attachment, cream the butter and sugar together until fluffy.
Scrape down the bowl before adding eggs.
Add eggs. Mix until combined.
Add dry ingredients to the wet.
Mix on low with a paddle attachment until just combined. Drizzle in vanilla.
Transfer dough to parchment paper.
Roll into a disk.
Chill for about 1 hour.
Press to flatten and roll between 2 pieces of parchment paper.
Roll dough to ½ inch.
Use 2.5 inch circle cookie cutters.
Place cookies onto a baking sheet with a silpat.
Bake for 12 min.
Let cool before decorating.