1. Preheat the oven to 350°F (180°C).
  2. Top 4 slices of bread with cheese and ham, then crown with the remaining slices of bread to make 4 sandwiches.
  3. Spread butter lightly and evenly over the outside of each sandwich.
  4. Using a serrated knife cut each sandwich into 12 cubes.  Lightly pack 4 cubes into each of 12 greased muffin cups.
  5. In a medium bowl, whisk together the remaining ingredients. Spoon the egg mixture over the cubes, slow and repeatedly to get good absorption.
  6. Let stand for 10 minutes.
  7. Bake for 30 minutes or until golden and set.
  8. Let stand for 15 minutes and then remove the muffins from their cups.
  9. Serve immediately or wrap individually and refrigerate.  May be kept in the refrigerator for up to 2 days. Serve warm or at room temperature.