Step 1: Preheat your oven to 325°F (160°C). Line a baking sheet with parchment paper.
Step 2: In a medium bowl, cream together the softened butter and sifted powdered sugar until light and fluffy. This should take about 3-5 minutes with an electric mixer. Ensure the mixture is well combined and pale in color.
Step 3: If adding optional flavorings (like vanilla extract or citrus zest), stir them in briefly until just combined.
Step 4: Gather the dough and gently form it into a ball. Do not overmix. If the dough is too soft to handle, flatten it into a disk, wrap in plastic, and chill in the refrigerator for 15-20 minutes.
Step 5: On a lightly floured surface or between two sheets of parchment paper, roll out the dough to about ¼-inch thickness. Using a small cookie cutter (or a knife to cut squares/rectangles), cut out your cookies.
Step 6: Carefully transfer the cut cookies to the prepared baking sheet, leaving about 1 inch between each cookie.
Step 7: Bake for 12-15 minutes, or until the edges are lightly golden. The centers may still look pale. Baking time can vary based on cookie thickness and oven.
Step 8: Remove from the oven and let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely. They will firm up as they cool.