The Collaborative International Dictionary of English v.0.48:

malted milk \malted milk\ n.
   1. A milkshake made with malt powder; also called simply a
      malted.
      [WordNet 1.5]

   2. A powder made of dried milk and malted cereals.
      [WordNet 1.5]

WordNet (r) 3.0 (2006):

malted milk
    n 1: a milkshake made with malt powder [syn: malted, malt,
         malted milk]
    2: powder made of dried milk and malted cereals