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

In a bowl, whisk together the flour, culinary lavender, baking soda, and salt. Set aside.

In a large mixing bowl, cream together the softened butter and sugar until light and fluffy, about 3-5 minutes.

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

Gradually add the dry mixture to the wet ingredients. Mix until just combined, being careful not to overmix.

Scoop tablespoon-sized portions of dough and roll them into balls. Place them on the prepared baking sheet with space in between.

Bake in the preheated oven for about 10-12 minutes or until the edges are lightly golden.

Let them cool on the sheet for a few minutes before transferring them to a wire rack to cool completely.

For the Lemon Buttercream Filling, beat together the softened butter, powdered sugar, lemon zest, lemon juice, and a pinch of salt until smooth and fluffy.

Once the cookies are cool, spread a generous amount of lemon buttercream on the bottom of half of the cookies and top them with the other half to create a sandwich.