Preheat the oven to 350 degrees F. Line two baking sheets with parchment paper and set aside. Using an electric mixer, cream the butter and sugar together on high until light and fluffy—3-5 minutes.
Scrape the bowl and add the vanilla, salt, and lavender. Turn the mixer on low and slowly add in the flour until just combined. Scrape the bowl again and mix for a few more seconds.
Dump the dough out onto a flour work surface. Roll it out until it's just under 1/4-inch thick. Then use a 2-inch round cookie cutter to cut of the shortbread cookies. Cut them close together to get as many out of the first batch as possible. Gather the dough, re-roll and cut. Place the cookies an inch apart of the baking sheets.
Gently press three firm blueberries into the top of each cookie. Then place them in the oven and bake until the edges are just barley golden brown—about 20 minutes. Cool on the baking sheets.
Once the cookies are cool, Place the cream cheese in a clean mixing bowl. Beat the cream cheese until light and fluffy, add the lemon curd one tablespoon at a time and mix in. Scrape the bowl and beat again, while slowly adding the powdered sugar. The powdered sugar is just to help the frosting "set" later. Don't over do it, or they'll be too sweet!
Place the lemon frosting in a piping bag with a large tip. Pipe a small dollop of lemon frosting on top of each shortbread cookie and top with a fresh blueberry. If you plan on eating them immediately, you can garnish them with freshly grated lemon zest.