1/2 cup cold water (110 degrees F/45 degrees C)
1/2 cup white sugar
1 cup buttermilk
1 teaspoon vanilla extract
1 egg
1 cup drained crushed ice
In a large glass or metal bowl, combine water, sugar, buttermilk, and vanilla extract. Whisk to combine. Stir in egg until all ingredients are thoroughly combined.
Pour into a tall glass or pipe and chill for 1 hour. Remove from freezer and thaw in refrigerator.