1. Lightly toast the ciabatta bread with a drizzle of olive oil.
2. Spread the mustard on the base bread and top with slices of ham.
3. Grate the cheese, and sprinkle generously on top of the ham.
4. Sprinkle a little bit of left-over cheese on top of the bread, and place both breads open faced (do not make a sandwich yet) in the oven until the cheese is melted and golden brown. This should take around 4-6 minutes.
5. Meanwhile fry the egg on medium-low heat with butter or oil. Once the sandwich is ready, remove
from the oven, place the top bread on the ham and cheese and generously spread the bacon béchamel on top of the sandwich.
6. Slide the fried egg on top of everything and serve.