Make a mint flavored simple syrup by boiling water and sugar with two bunches of roughly torn and bruised mint in large sauce pot. Boil just until the sugar dissolves completely. Cool and strain the mint out of mixture.
Add bottle of whisky to the infusion. Stuff the empty whisky bottle with last bunch of fresh mint leaves and fill with the simple syrup/whiskey mixture.
Cap and put in freezer overnight. It will freeze to a slushy consistency for serving.
Glasses: dip the rim of each glass in egg white, then in sugar for a frosted appearance and chill. Fill with mint julep mixture straight from the frozen bottle and garnish with a mint or lavender sprig.