Preheat your oven to 350°F (175°C) and whisk together the flour, baking powder, and salt in a mixing bowl.

Cream together the butter and sugar using a hand mixer until light and fluffy (2-3 minutes).

Beat in the egg, vanilla extract, and lemon zest until well combined.

Gradually add the flour mixture to the wet ingredients, mixing on low speed until combined and fold in the lavender.

Scoop portions of the cookie dough onto a baking sheet lined with parchment paper, spacing them 2 inches apart.

Bake in the preheated oven for 10-12 minutes or until edges are lightly golden, keeping centers soft.

Cool cookies on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.

Beat together the butter and powdered sugar for frosting; add lavender, cream, and vanilla until light and fluffy.

Spread frosting on one cookie and sandwiched with another, repeating the process until all cookies are paired.