Bring the milk and vanilla seeds to a simmer in a heavy medium saucepan. Add the malted milk powder and brown sugar to the hot milk, whisking until dissolved. Remove 1 cup milk mixture and puree in a blender, about 2 minutes. Divide the milk among 4 mugs and top with the pureed milk and a sprinkle of cinnamon.
BYOC: This is a perfect drink for after spending some time out in the cold. Make this for the kids and add a little light rum for the adults.