10 oz. pkg. chopped spinach, thawed
5 lg. russet potatoes
1 lg. red onion, thinly sliced
1/4 lb. thinly sliced prosciutto or cooked ham, cut into slivers
Three cheese sauce (recipe follows)
1/4 c. freshly grated Parmesan cheese

Squeeze spinach, set aside. Peel potatoes, slice into 1/8 inch slices. Butter 13 x 9 inch pan, arrange 1/3 potatoes overlapping to cover bottom. Cover evenly with 1/2 onion, 1/2 prosciutto and 1/2 spinach, then spoon 1/3 cheese sauce over. Repeat, finish with potato and then cheese. To make ahead, cover and chill. Let stand at room temperature 1 hour. Bake covered at 375 degrees for 30 minutes, uncover and continue baking until tender and browned, about 1 hour. Sprinkle with Parmesan and bake 5 minutes. Let stand 10 minutes.

CHEESE SAUCE:

1/2 c. butter
1/2 c. flour
2 c. milk
2 c. chicken broth
1/4 tsp. nutmeg
4 oz. each shredded havarti, provolone and Swiss cheese
Pepper to taste

Heat butter and flour until bubbling; whisk in milk, chicken broth and nutmeg until boiling. Stir in cheeses and pepper to taste.