Frosting: Cream together powdered sugar and shortening. Add lemon juice then water as needed to reach desired consistency. Set aside,
cake
Preheat oven to 350 degrees. In a medium bowl combine the flour, baking powder, and salt. Set aside.
Cream the butter and sugar together at medium-high speed until pale and fluffy,
about 4-6 minutes.
With the mixer running on low-speed, add the eggs one at a time, then beat in the lavender extract and lemon juice. Beat on medium-high speed until combined.
With the mixer on low, add about one-third of the flour mixture and mix until almost combined, then add half the buttermilk and mix until just combined. Repeat with another third of flour mixture and then the last half of the buttermilk, ending with the last third of the flour.
Bake cupcakes at 350 until inserted toothpick comes out clean, about 12 to 14 minutes.