- Chop the eggs up and put into a bowl with the mayonnaise and a pinch of salt and pepper, mix well.
- Spread the mixture onto 2 slices of the bread and top with fresh watercress.
- Finish with the remaining two slices, cut off the crusts and cut into triangles.
- Serve immediately or store in the fridge in an airtight container until ready to use.
To spice it up a little: add chives and/or a pinch of cayenne pepper to the egg mayonnaise.