Preheat your oven to 350°F (180°C) and line your baking sheets with parchment paper.

In a large mixing bowl, whisk together the all-purpose flour, cornstarch, baking powder, and a pinch of salt.

Cream the softened salted butter and granulated sugar together using an electric mixer. Add in the lemon zest and dried lavender buds, beating until light and fluffy.

Crack the room-temperature egg into the mixture and blend until fully incorporated.

Slowly add the dry ingredients to the wet mixture, mixing just until combined.

Drop rounded balls of dough onto prepared baking sheets, spacing them about 2 inches apart.

Gently press down on each ball to flatten them to about 1/3 inch thick.

Bake for 12-15 minutes, checking around the 10-minute mark until edges turn golden.

Remove trays from oven and let cookies cool for about 5 minutes, then transfer to a wire rack.

Whisk together the powdered sugar, fresh lemon juice, and lavender extract to form the glaze.

Spoon the glaze over each cooled cookie and garnish with lavender buds and extra lemon zest.

Let the glazed cookies sit at room temperature for about 30 minutes to allow the glaze to set.