Step 1: Preheat your oven to 350°F (175°C) and line two large baking sheets with parchment paper.
Step 2: In a large bowl, cream together the softened butter and granulated sugar until light and fluffy, about 3-5 minutes.
Step 3: Beat in the egg and vanilla extract until well combined. Stir in the fresh lemon zest and lavender if using.
Step 4: In a separate bowl, whisk together the flour, baking powder, and salt.
Step 5: Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
Step 6: Chill the dough in the refrigerator for at least 30 minutes to improve texture and flavor.
Step 7: Scoop tablespoon-sized balls of dough onto the prepared baking sheets, spacing them 2 inches apart.
Step 8: Bake for 10-12 minutes, or until the edges are just lightly golden.
Step 9: Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.