1. Beat the evaporated milk and egg yolks together over low heat for about five minutes. The mixture should thicken slightly.
  2. Let cool.
  3. Combine all ingredients into blender and pulse until thickened and frothy. If your blender can not fit all ingredients, work in batches.
  4. Transfer to pitcher or container and refrigerate until chilled.
  5. Pour into mug, garnish with nutmeg or cinnamon and serve.