01 - Pulse the sugar and lilac blossoms in a food processor until the flowers are finely chopped and the sugar is fragrant and pale purple. Set aside.
02 - Whisk together the flour, baking powder, and salt in a bowl.
03 - Cream the butter and prepared lilac sugar together in a large bowl until light and fluffy.
04 - Add the egg and vanilla extract to the butter mixture, beating until fully combined.
05 - Gradually add the dry ingredients to the wet mixture, mixing until just incorporated.
06 - Divide the dough in half, shape into discs, wrap in plastic wrap, and chill for at least 1 hour.
07 - Preheat the 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. Cut into shapes using cookie cutters.
09 - Place cookies on prepared sheets and bake for 8-10 minutes, or until edges are just golden.
10 - Cool on the pan for 5 minutes, then transfer to a wire rack to cool completely.