Put the spinach in a saucepan with a little salt. Cover and cook over a medium heat for about 5 minutes. Drain.
Heat 2 tbsps of the butter in a small frying pan . Saute the bread triangles over a low heat until golden and crisp. Remove and keep warm then wipe out the pan.
Half fill a large skillet with water for use as a double boiler. Bring to a boil then reduce to a simmer.
Melt the remaining 1 tbsp butter in the small frying pan, add the prawns and cook for about 3 minutes then remove from the heat.
Beat the eggs with the milk , salt and pepper in a small bowl. Add to the pan with the prawns and place inside the larger pan, double boiler fashion. Stir constantly with a wooden spoon until the eggs just begin to set.
Gently mix in the spinach and continue to cook until the eggs are set but still quite soft. Serve with the bread triangles.