Begin by creaming the softened butter and confectioners' sugar in a large mixing bowl. Beat the mixture on medium speed for 3–4 minutes until it turns light and fluffy. For a more flavorful touch, add your chosen extract—vanilla, lemon, or orange—at this stage and blend briefly.
In a separate bowl, sift together the flour and cornstarch. Gradually incorporate the dry ingredients into the creamed butter mixture, mixing only until the dough comes together. Avoid overmixing to maintain a tender cookie texture.
Divide the dough into 36 equal portions. Roll each piece into a smooth ball and arrange them on a parchment-lined baking tray. Alternatively, you can place the balls on a lightly floured plate to prevent sticking. Gently flatten the tops using a fork dipped in cornstarch or flour, and decorate with sprinkles for a festive touch.
Chill the dough balls in the refrigerator for about 2 hours or until they are very firm to the touch. For a quicker option, transfer them to the freezer to speed up the process.
While the dough chills, prepare your oven by preheating it to 300°F. When ready, bake the cookies in batches, arranging 12 cookies per tray. Bake for 19–20 minutes, or until the tops appear set but not browned.
Remove the cookies from the oven and let them cool on the baking tray for a few minutes to firm up. Once cooled, transfer them to a wire rack to cool completely before serving or storing.