Beat butter in a mixing bowl till soft and creamy. Add powdered sugar and beat till smooth.

Stir in flour till mixture is well combined; press dough together till it forms a ball.

Flatten dough and place in a gallon sized ziplock bag, close the bag tightly. Use a rolling pin to roll the dough 1/4" thick inside the bag. It will form a perfect square inside the bag!

Chill dough for at least 30 minutes. Carefully cut away the sides of the bag. Use a knife, pizza cutter, or pastry wheel to cut the dough into rectangle shapes.

Place cookies on ungreased cookie sheets about an inch apart. Place pans in the refrigerator.

While the cookies are chilling, preheat the oven to 325 degrees. Bake cookies for 15-18 minutes or till the bottom edges are barely turning light brown.

Let cookies cool on the pan for a few minutes, then remove to cooling racks.

If desired drizzle cooled cookies with melted chocolate.