This is a recipe from the Post Gazette that is suppose to be the original.
Frank Blandi's Original Devonshire Sandwich
Cream Sauce:3/4 stick butter, melted1 cup flour1/4 pound Cheddar cheese, grated1 pint chicken broth1 pint hot milk1 teaspoon salt
Melt butter in deep pan and add flour, stirring constantly. Add chicken broth and then hot milk, stirring all the while. Add cheese and salt. Bring to boil, then cook slowly for 20 minutes, still stirring. Cool to lukewarm. Beat with wire whip until smooth before using. This makes enough sauce for 6 Devonshire sandwiches.
For each sandwich:1 slice toast, crusts trimmed off3 slices crisp bacon5 thin slices cooked turkey breastCream Sauce, recipe aboveMelted butter Parmesan cheese and paprika
Preheat oven to 450 degrees.
In each flat, individual oven-proof casserole dish, place 1 slice of toast and top with 3 slices bacon. Add 5 thin slices of cooked turkey breast. Cover completely with cream sauce. Sprinkle with a little melted butter, then with the combined Parmesan cheese and paprika. Bake 10 to 15 minutes or until golden brown.