Preheat oven to 350 degrees F (175 degrees C). Line a baking sheet with waxed paper and grease the paper.
Whisk flour, sugar, and baking powder in a bowl. Stir butter and egg into flour mixture until smooth; add vanilla extract and lavender. Gently mix again until thoroughly combined.
Drop cookie dough by tablespoon about 2 inches apart onto prepared baking sheet.
Bake in the preheated oven until cookies are fragrant and edges turn light golden brown, 10 to 15 minutes.
