01 - Pulse sugar and lilac blossoms in a food processor until flowers are finely chopped and sugar is fragrant and pale purple. Set aside for later use.
02 - Whisk together flour, baking powder, and salt in a medium bowl until thoroughly blended.
03 - Beat butter and prepared lilac sugar together in a large bowl until light and fluffy, approximately 2-3 minutes.
04 - Add egg and vanilla extract to the butter mixture, beating until fully incorporated.
05 - Gradually add dry ingredients to the wet mixture, mixing until just combined. Avoid overmixing to prevent tough cookies.
06 - Divide dough in half, shape into discs, wrap tightly in plastic wrap, and refrigerate for at least 1 hour until firm.
07 - Preheat oven to 350°F and line baking sheets with parchment paper.
08 - Roll out dough on a lightly floured surface to 1/4 inch thickness and cut into desired shapes using cookie cutters.
09 - Place cut cookies on prepared baking sheets and bake for 8-10 minutes until edges are just beginning to turn golden.
10 - Let cookies rest on the baking pan for 5 minutes, then transfer to a wire rack to cool completely before serving.