1In a small saucepan, combine the flour, salt and pepper. Gradually stir in milk until smooth. Bring to a boil over medium heat; cook and stir for 1 minute or until thickened. Reduce heat to low; keep warm and stir occasionally. In a double boiler over simmering water, constantly whisk the egg yolk, lemon juice and water until mixture begins to thicken and coats the back of a metal spoon. Reduce heat to low. Slowly drizzle in melted butter, whisking constantly. Whisk in milk mixture. Cover until sandwich is done- don't want the yummiest part cold!
When you are done with the sauce heat a large skillet on medium heat. Chop shrimp, crab, and onion. Saute spinach, crab, onion, and shrimp until lightly browned and heated all the way through. While cooking beat until frothy in a medium bowl egg whites. Pour over top of shrimp mixture and cook until eggs are no longer runny about 3 minutes. Toast bread, add shrimp and egg mixture, top with sauce. Breakfast is served!
Hint: Do not add too much shrimp and crab I did this the first time I created this recipe and it was too fishy.