Virginia, this is not exactly what you are looking for but very good and perhaps you could just "doctor it up" to get the casserole you want.

DELMONICO POTATOES
9 medium potatoes, cooked in salted water for about 25 minutes or until they are fork tender. Cool for at least 1 hour. Peel and dice potatoes.

Sauce:
1/3 cup butter
1/3 cup flour
1/2 to 1 pint half and half
1/8 tsp. pepper

dry bread crumbs (from 3 slices of bread)

Melt butter over medium heat, stir in flour and cook for 1 min., stirring constantly. Continue to stir constantly and gradually add the 1/2 and 1/2 until desired thickness, then stir in pepper and 2 tsp. salt. Add the sauce to the diced potatoes (carefully). Bake at 375 for 25 min. in greased 12" x 8" baking dish. Add the cheese and bread crumbs to the top of the potatoes and continue 'til cheese melts and sauce becomes bubbly. If sauce becomes too thick, simply add more 1/2 & 1/2, stir and heat.