Weigh or measure the sugar and set it aside. Next, weigh or measure the flour, baking powder, and salt in another bowl. Finally, I run a whisk through to blend.
Add the butter and sugar to your mixer bowl and blend on medium mixer speed for 3 or 4 minutes. Now add the egg and the champagne reduction and mix. Scrape down the bowl sides turn the mixer on to a slow speed, and gradually add the flour mixture. Don't overbeat; you can bring any small pieces or loose flour together once you place the dough on the pastry mat.
Once the cookie dough is placed onto the pastry mat, you can knead the dough until all the dough is together into a large disk shape. Next, divide the dough in half. Take each half and make a flat round disk. Next, you want to wrap each disk in plastic wrap. Place both wrapped disks into the refrigerator and chill for 30 minutes.
Take the dough out of the fridge and unwrap one of the disks. Place the disk on a lightly floured surface. I have bands on the ends of my rolling pin for ¼" thickness, which is the perfect thickness for your cookies. The star shape cookie cutter I used was 3 ¼" across from point to point. It was the next to the smallest size of the 4 in the Wilton Cookie Cutter star pack.
Roll out the dough, place 12 cutout stars on a parchment-lined cookie sheet and bake at 350°F (175°C or 180°C) for 7-9 minutes. Then, move to a cooling rack to finish cooling.