Cut the croissants lengthwise and lightly fry each half in a hot pan with butter.
Meanwhile, cook the scrambled eggs on a low heat until creamy. Finish with a knob of butter.
To serve, place half of the croissant on a serving plate, add a handful of watercress, add the scrambled eggs and season with salt and pepper. Garnish with parmesan shavings, than place the other half of the croissant on top.