Icy Vanilla-Rum Malted Milkshake

Dazzle guests with this made-to-order icy beverage that couldn't be easier. This recipe was developed to go in the Magic Bullet--that inexpensive blender that whips up one drink at a time. (If you don't have one, use a regular blender; just start with 2/3 cup ice and add more as needed.) Use bagged, small-piece ice over large, hard chunks. For kids, nix the liquor.