Preheat the oven to 350°F (175°C) and prepare two 8-inch round cake pans by greasing and flouring them.

In a large bowl, cream together softened butter and granulated sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition.

Stir in the lemon zest, lemon juice, and buttermilk until combined.

In another bowl, whisk together the flour, baking powder, salt, and dried lavender. Gradually add to the wet mixture, mixing until just combined.

Pour the batter evenly into the prepared cake pans and smooth the tops.

Bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.

Allow cakes to cool in the pans for 10 minutes, then invert onto a wire rack to cool completely.

For the frosting, beat the softened butter until creamy, gradually add powdered sugar and lemon juice, mixing until smooth.

Once the cakes are cool, frost one layer, add the second layer, and frost the top and sides.

Garnish with additional lavender if desired and serve at room temperature.