Preheat oven to 350° F. Spray 2 sheet pans with nonstick cooking spray. Place the butter and sugar together in an electric mixing bowl using the paddle attachment and cream on medium speed until well combined.
Add the flour, cornstarch and vanilla extract to the butter mixture and beat well on medium speed.
Put the mixture into a piping bag fitted with a large star tip, and pipe it onto the cookie sheets in short lines (about 2 inches long) leaving a space between each. Bake for 15 minutes until pale golden.