From the Wall Street Journal:

Fortunately, the origins of America’s most celebrated turkey sandwich are unchallenged and probably unchallengeable. I speak of the Hot Brown, devised in 1926 in Louisville’s grand Brown Hotel by Chef Fred K. Schmidt as a novelty replacement for ham and eggs at the midnight suppers that followed big dances at the hotel.

You can still experience this pinnacle of turkey haute cuisine at the Brown Hotel in its hallowed traditional form. Nominally a sandwich, the Hot Brown is actually a casserole of sliced turkey breast, toast and bacon covered with an egg-thickened Mornay sauce (white sauce with Parmesan; see recipe).

Here’s the Brown Hotel recipe:

Brown Hotel
4 ounces butter
Flour to make a roux (about 6 tablespoons)
3 to 3 1/2 cups milk
1 beaten egg
6 tablespoons grated Parmesan cheese
1 ounce whipped cream (optional)
Salt and pepper to taste
Slices of roast turkey
8 to 12 slices of toast (may be trimmed)
1/4 beefsteak tomato
Extra Parmesan for topping
8 to 12 strips of fried bacon

• Melt butter and add enough flour to make a reasonably thick roux (enough to absorb all of the butter). Add milk and Parmesan cheese. Add egg to thicken sauce, but do not allow sauce to boil. Remove from heat. Fold in whipped cream. Add salt and pepper to taste.

• For each Hot Brown, place two slices of toast on a metal (or flameproof) dish. Cover the toast with a liberal amount of turkey. Pour a generous amount of sauce over the turkey and toast. Add tomato on sides of dish. Sprinkle with additional Parmesan cheese. Place entire dish under a broiler until the sauce is speckled brown and bubbly. Remove from broiler, cross two pieces of bacon on top, and serve immediately.

And if you’re still not tired of turkey, try this (I don’t think it sounds very good):

… the Cold Brown, an obscure cousin to the hot one. As she remembers it from many a lazy summer lunch of her Kentucky girlhood, the Cold Brown is an open-faced sandwich composed of sliced turkey, lettuce, tomato, hard-boiled egg and Thousand Island dressing.