ice milk

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A smooth, sweet, cold food prepared from a frozen mixture of milk products, usually containing 3 to 6 percent butterfat, 11 to 14 percent nonfat milk solids, and 12 to 15 percent sugar.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A dessert that resembles ice cream but is made of milk rather than cream.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun similar to ice cream but made of milk