Amorous Poached Egg Sandwich With Swiss Cheese Sauce

Directions

1. 1
   In a small saucepan, melt 1 tablespoon butter over medium heat.
2. 2
   Add 1 tablespoon onion and cook, stirring, until softened, about 3 minutes.
3. 3
   Whisk in the flour and stir for 1 minute.
4. 4
   Whisk in the milk and simmer for 2 minutes, then whisk in the cheese and season to taste with salt and pepper.
5. 5
   Cover the cheese sauce and set aside.
6. 6
   Melt the remaining 1 tablespoon butter in a medium skillet over medium heat.
7. 7
   Add the remaining onion and cook, stirring, until golden, about 7 minutes.
8. 8
   Add the spinach and cook until soft, 3 to 4 minutes.
9. 9
   Season to taste with salt and pepper.
10. 10
    Fill a small nonreactive skillet with 1 inch of water.
11. 11
    Add the vinegar and a pinch of salt and bring to a boil.
12. 12
    Meanwhile, toast the English muffin.
13. 13
    Crack the eggs into saucers, then slide them into the boiling water and simmer until desired doneness, about 3 minutes for lightly poached.
14. 14
    Transfer to a plate using a slotted spoon.
15. 15
    Re-warm the cheese sauce over low heat.
16. 16
    Top each English muffin half with 1 prosciutto slice, 1 tomato slice, half the spinach, some cheese sauce, another prosciutto slice, a poached egg and more cheese sauce.