Beat butter in a large bowl until light and fluffy. Add confectioners’ sugar and beat until smooth.

Whisk flour and cornstarch together in a separate bowl. Gradually add flour mixture to butter mixture and mix until a soft dough forms. Cover and refrigerate dough until firm, about 1 hour.

Preheat the oven to 300 degrees F (150 degrees C).

Shape dough into 1-inch balls and place about 1 1/2 inches apart on ungreased baking sheets. Flatten each ball slightly with a lightly floured fork. Flatten with lightly floured fork.

Bake in the preheated oven until the edges are lightly browned, about 18 to 20 minutes. Let cookies cool on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.