Preheat the oven to 350 degrees F (175 degrees C). Line a baking sheet with parchment 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 until thoroughly combined.

Drop cookie dough by tablespoon about 2 inches apart onto the prepared baking sheet.

Bake in the preheated oven until cookies are fragrant and edges turn light golden brown, 10 to 15 minutes.