Blend together egg whites and white sugar in blender for 15 seconds. Add Pisco and lime juice and blend for 15 seconds.
Put crushed ice into shaker and add Pisco sour mix to about 2/3 full. Shake and strain into small glasses. Garnish with a sprinkle of brown sugar. You can also garnish with a drizzle of browned, melted butter.
Repeat shaker process with rest of mix, only adding more crushed ice as needed.
Makes about 16 servings - enough for 8 people, 2 servings each.