Preparation
Slice the avocado and tomato into thin slices.
Snip the watercress and set aside.
Beat the eggs with pepper and salt.
Cooking the cheese omelet
Heat a frying pan over medium heat.
Place the slices of cheese side by side in the pan, covering the bottom completely. Let it melt.
Pour the beaten eggs over the cheese and let it cook until the egg is done and the cheese is nicely golden brown.
Toasting the bread
Slice the sandwich open and place both halves with the inside facing down in the pan. Let it cook briefly until lightly crispy.
Assembling the sandwich
Remove the sandwich from the pan and layer it with avocado, tomato, San Daniele ham, optionally anchovies, and watercress.
Serving
Serve immediately while the sandwich is still warm.