Yes, I know it is the middle of winter... but I was totally craving one of these the other day.
3-4 oz. frozen orange juice concentrate
1/4 c. sugar
1/2 c. milk
1/2 c. water
1 tsp. vanilla
~20 ice cubes
Put all ingredients except for ice in a blender and mix well. While blending, add ice in small batches until desired consistency is reached.