01 - Pulse granulated sugar and fresh lilac blossoms in a food processor until flowers are finely chopped and sugar becomes fragrant with a pale purple tint. Set aside for later use.
02 - Whisk together all-purpose flour, baking powder, and salt in a medium bowl until thoroughly blended. Set aside.
03 - Beat room temperature unsalted butter and prepared lilac sugar in a large bowl until mixture becomes light and fluffy, approximately 2-3 minutes.
04 - Incorporate large egg and vanilla extract into the butter-sugar mixture, beating until fully combined and smooth.
05 - Gradually add dry ingredient mixture to the wet ingredients, mixing until just incorporated. Avoid overmixing to prevent tough cookies.
06 - Divide dough in half, shape into flat discs, wrap tightly in plastic wrap, and refrigerate for at least 1 hour until firm enough to roll.
07 - Preheat oven to 350°F and line baking sheets with parchment paper.
08 - On a lightly floured surface, roll chilled dough to 1/4 inch thickness. Cut into desired shapes using cookie cutters.
09 - Arrange 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 baking sheets for 5 minutes, then transfer to a wire rack to cool completely before serving or storing.