Preheat the oven to 375 degrees.
Using a 2-inch round cookie cutter (or a spice bottle) as a guide, trace 24 circles on to 2 separate pieces of parchment paper. Make sure that each circle is at least 1 inch apart.
Grease and line two large baking sheets with the parchment paper (making sure that the side with the pencil tracings are face down).
Using a stand mixer fitted with the paddle attachment or a hand mixer, cream the butter and powdered sugar until fluffy (about 1-2 minutes).
Sift in flour and corn starch. Beat until just combined.
Prepare a piping bag with a star piping tip. Spoon cookie dough into piping bag.
Pipe the cookie dough into swirled rounds (ending with a peak at the center), using the round tracings as a guide.
Refrigerate the piped cookie dough for at least 30 minutes so that the shape of the cookie sets.
Bake the cookies for 10-12 minutes or until the bottoms and edges are light brown.
Let cookies cool to room temperature before assembling.