Sift together cornstarch, icing sugar (or powdered sugar), and flour in a bowl.

Blend in softened butter until a soft, smooth dough forms.

Shape the dough into 1-inch balls.

Chill the dough balls in the refrigerator for 30-60 minutes.

Preheat oven to 300°F (150°C).

Place the chilled dough balls 1 1/2 inches apart on a cookie sheet.

Flatten each dough ball slightly with a floured fork (optional).

Bake for 15-20 minutes. Watch closely to ensure they don't brown.

Transfer the cookies to a wire rack and let cool completely.