Slice the avocado and tomato thinly.
Cut the watercress and set aside.
Beat the eggs with salt and pepper.
Heat a frying pan over medium heat.
Place the slices of cheese next to each other in the pan so that the bottom is completely covered. Let them melt.
Pour the beaten eggs over the cheese and cook until the eggs are set and the cheese turns golden brown.
Open the bun and place both halves, cut side down, in the pan. Let them cook briefly until slightly crispy.
Remove the bun from the pan and layer with avocado, tomato, San Daniele ham, optionally anchovies, and watercress.
Serve immediately while the sandwich is still warm.
Tips
No San Daniele ham at home? You can also use Parma ham or another cured ham.
Prefer vegetarian? Leave out the ham and anchovies and add some extra vegetables or grilled peppers.
For a spicy touch, you can sprinkle a pinch of chili flakes over the omelette.