Preheat to 375 degrees F.
Sift the flour, cornstarch and salt into a large bowl and whisk together.
In a standing mixer fitted with a paddle attachment, cream butter and sugar together.
Add eggs one at a time then the vanilla while mixing on low.
Scrape the bowl down and mix in the dry mixture.
Separate dough into two disks. Wrap in plastic and chill for about an hour. I like to roll my dough out a bit between two sheets of plastic wrap at this point so there's less rolling later on.
Roll chilled dough to a 1/4 inch thickness.
Cut out a shape using a medium to large cookie cutter. Cut out the window shape on the inside using a smaller shape.
Poke a small hole at the top of the cookie. This is for the ornament hook.
Place cookies on a silpat lined baking sheet.
Add hard candies to a ziplock bag. Choose a brand and flavor of hard candies that you enjoy.
Crush up, then add to the inside of the cookies. Distribute evenly.
Bake for 12 minutes at 375F then allow to cool on baking sheet.
Add ornament hook if hanging.