Grind lavender flowers in a clean coffee grinder.  

Melt chocolate, milk, and lavender together in a double boiler.  Add butter.  Stir until smooth and melted.  

Pour into a pan (approximately 9" square) lined with wax paper.  Cover with cling film.  Chill overnight.

Cut into 1" squares.  Sprinkle fresh lavender on top for garnish, if desired.