01 - Pulse sugar and lilac blossoms in a food processor until flowers are finely chopped and sugar becomes fragrant with pale purple hue. Set aside for use.
02 - Whisk flour, baking powder, and salt together in a medium bowl until evenly distributed.
03 - Beat butter and prepared lilac sugar in a large bowl until mixture is light, fluffy, and well combined.
04 - Add egg and vanilla extract to butter mixture. Beat until fully incorporated and smooth.
05 - Gradually add dry ingredients to wet mixture, mixing until just combined. Avoid overworking the dough.
06 - Divide dough in half and shape into discs. Wrap tightly in plastic wrap and refrigerate for at least 1 hour.
07 - Preheat oven to 350°F. Line baking sheets with parchment paper and set aside.
08 - Roll chilled dough on lightly floured surface to 1/4 inch thickness. Cut into desired shapes using cookie cutters.
09 - Arrange cookies on prepared baking sheets. Bake for 8 to 10 minutes until edges are just beginning to turn golden.
10 - Let cookies rest on baking sheets for 5 minutes, then transfer to wire rack to cool entirely before serving.