Preheat oven to 350℉. Grease and flour a 8½ by 4½ inch bread pan.
In a small bowl melt butter in microwave, or in a small saucepan on the stove. Let cool.
In a mixing bowl, whisk together flour and baking powder, set aside.
In the bowl of a food processor, add sugar and lemon zest. Pulse 4-5 times to combine. Add lemon juice, eggs and vanilla extract and pulse a few times to combine.
Whisk the cooled butter to blend the milk solids back in. While the food processor is running, drizzle the butter into the sugar mixture.
Fold the liquid mixture into flour mixture until just combined. Pour into the prepared loaf pan.
Bake for 15 minutes at 350℉. Reduce temperature to 325℉ and continue baking until lightly golden and toothpick inserted in center comes out clean, about 30 minutes.
Remove pound cake from oven, let cool on a wire rack for 10 minutes. Then remove from pan and let cool completely.
In a small bowl, add powdered sugar, lavender extract and a tablespoon of milk. Adjust to desired consistency with additional milk if desired. Tint to desired color with purple sweet potato powder or food coloring.
Place pound cake on serving plate, drizzle glaze over cake. Decorate with lemon slices and lavender blossoms (optional).