Preheat oven to 200 degrees F.
Prepare the Sauteed Spinach then transfer to a coloander set over a bowl to drain. Keep warm while you prepare the remaining components. Prepare the Mornay Sauce and keep warm while you prepare the remaining components. Prepare the Crispy Potato Cakes and keep warm in the oven while you poach the eggs.
Add the spinach to a skillet set over medium low heat. Stir in two-thirds of the Mornay sauce and heat until creamy. Remove from the heat and set aside covered until ready to use.
Poach the eggs: break the eggs into individual saucers or cups. Fill a medium skillet halfway with water. Add the vinegar and salt and bring to a boil. Pour eggs into water, cover the skillet and remove from the heat. Allow to sit 4 to 5 minutes. When the eggs are ready, divide the potato cakes evenly between 2 dinner plates and top each with some of the creamed spinach. Remove the eggs from the skillet with a slotted spoon and gently place on top of the creamed spinach and potato cakes. Season with salt and freshly ground black pepper, to taste. Serve with the remaining Mornay Sauce.