Follow these steps carefully to ensure a perfect dough consistency, which is key for both piping and achieving the ideal texture. Patience in the creaming and chilling stages will be rewarded with flawless cookies.

1. Cream the Butter and Sugar: In a large mixing bowl, or the bowl of a stand mixer fitted with the paddle attachment, place the softened unsalted butter. Beat on medium speed for about one minute until it is smooth and creamy. Add the sifted powdered sugar and the salt. Start the mixer on low speed to prevent a sugar cloud, then increase to medium-high. Beat the butter and sugar mixture for a full 3 to 5 minutes. This step is critical. You are not just combining the ingredients; you are whipping air into the mixture. The final result should be very pale, light, and fluffy, almost like a buttercream frosting. Scrape down the sides and bottom of the bowl a couple of times to ensure everything is evenly incorporated.
2. Incorporate the Egg and Vanilla: With the mixer on medium-low speed, add the room temperature egg and the vanilla extract. Mix until they are just fully combined, which should take about 30-45 seconds. Be careful not to overmix at this stage. The mixture should look smooth and emulsified. Scrape the bowl down once more.
3. Add the Flour: Turn the mixer off. Add the sifted all-purpose flour to the wet ingredients all at once. Turn the mixer on to its lowest possible speed and mix just until the flour is incorporated and no dry streaks remain. This is another crucial point: do not overmix the dough once the flour is added. Overmixing develops gluten, which will result in tough, dense cookies instead of light, tender ones. The final dough should be soft, smooth, and pliable.
4. Prepare for Piping: Transfer the soft dough into a large piping bag fitted with a large open star tip (like a Wilton 1M or 2D). A large tip is essential, as the dough is thick and will be difficult to push through a small opening. To make filling the bag easier, place it in a tall glass and fold the top edges over the rim of the glass.
5. Chill the Piped Dough: Line two large baking sheets with parchment paper. This prevents sticking and promotes even baking. Pipe the dough onto the prepared sheets in your desired shapes. Classic rosettes or swirls are traditional. To make a rosette, hold the piping bag perpendicular to the baking sheet and squeeze from the center outwards in a circular motion, about 2 inches in diameter. Leave at least 1.5 inches of space between each cookie as they will spread slightly. Once you have piped all the dough, place the entire baking sheets in the refrigerator to chill for at least 30-60 minutes. Do not skip this step! Chilling the piped cookies solidifies the butter, which is the secret to preventing them from spreading too much in the oven and helps them retain their beautiful piped shape.
6. Preheat and Bake: While the cookies are chilling, preheat your oven to 350°F (175°C). Position an oven rack in the center of the oven for the most even heat distribution.
7. Bake to Golden Perfection: Remove one baking sheet from the refrigerator and place it directly into the preheated oven. Bake for 12-15 minutes. The exact time will depend on your oven and the size of your cookies. The cookies are done when the edges are a light golden brown, but the centers still look pale. They will continue to set as they cool.
8. Cool Completely: Remove the baking sheet from the oven and let the cookies cool on the sheet for 5 minutes. This allows them to firm up enough to be moved. After 5 minutes, carefully transfer the cookies to a wire rack to cool completely. Repeat the baking process with the second sheet of chilled cookies. It is crucial that the cookies are completely cool before storing to maintain their crispness.