Place shrimp on to skewers, on a heated cast iron pan or grill cook shrimp about 5 minutes each side until opaque inside, do not overcook or shrimp will became tough.
Lemon Basil Aioli
Blend lemon juice, egg yolk, oil, garlic and basil with some salt and pepper until thick and smooth in a blender or food processor.
Cut bread, lay shrimp down, place watercress on top and slather the top of the bread with the Lemon Basil Aioli.