Preheat the oven to 325 degrees F (165 degrees C).
In a large bowl, beat the butter and confectioners' sugar with an electric mixer until light and fluffy. Combine the flour and cornstarch; beat with the mixer for 5 to 10 minutes. The batter needs to be soft and fluffy.
Fit a cookie press with a star disc and fill with cookie dough. Press cookies onto ungreased cookie sheets. Sprinkle with edible glitter.
Bake for 20 to 25 minutes in the preheated oven. They will not brown on top so peek at the bottom of a cookie after 20 minutes. Cool cookies on the cookie sheet for a few minutes before transferring to wire racks to cool completely. Store cookies in an airtight tin for up to two weeks.