In a medium saucepan, bring sugar and water to a boil. Lower heat to medium-low and add cranberries to saucepan.
Cook for about 10-15 minutes, until cranberries begin to burst. Add ginger and vanilla and let cook another 1-2 minutes.
Remove mixture from heat. Using the back of a spoon, mash up cranberries as much as possible. Alternately, you can put the mixture in a blender to purée.
Put mixture in a mason jar or bowl to cool (place in refrigerator to speed up cooling time).
In a blender, blend ice cream and milk together.
Put a couple tablespoons of cooled cranberry mixture in tall glass and pour in ice cream and milk mixture.
Serve with a straw, but you may need a spoon, too!