Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large bowl, beat the softened butter and granulated sugar together until light and fluffy, about 2-3 minutes.

Add in the egg, vanilla extract, and lemon zest, mixing until fully incorporated.

Gradually add the dry ingredients to the butter mixture, mixing just until combined. Be careful not to overmix.

On a lightly floured surface, roll out the dough to about ¼ inch thickness and cut out the cookies.

Bake for 8-10 minutes, or until the edges are just starting to turn golden. Allow them to cool completely on a wire rack.

In a large bowl, beat the softened butter until creamy.

Gradually add in the powdered sugar, a little at a time, until fully incorporated.

Mix in the ground culinary lavender, heavy cream, and vanilla extract. Add food coloring if desired.

Continue to beat the mixture until light and fluffy, about 2-3 minutes.

Once the cookies are completely cool, spread or pipe a generous layer of lavender buttercream onto the flat side of half the cookies.

Place another cookie on top, gently pressing down to create a sandwich.

Pipe a small swirl of lavender buttercream on the top of each assembled sandwich cookie.

Decorate each cookie with a thin lemon slice and a fresh lavender sprig.