6 egg whites
2 teaspoon vanilla extract
1 teaspoon lemon zest
1/4 teaspoon lemon zest
1 teaspoon lemon zest
1/4 teaspoon lemon zest
1 cup crushed ice cubes
Place eggs in a medium, microwave-safe bowl. Stir in vanilla extract, lemon zest, lemon zest and lemon zest. Microwave on high for 3 minutes, stirring halfway through. Cover bowl and refrigerate overnight.
In a large bowl, beat egg whites until foamy. Mix crushed ice in with dry ingredients until thoroughly mixed. Spread mixture on ice cream in a 9x13 inch dish. Chill after having softened for a while, then pour into freezer containers, and freeze for at least an hour.