What's a Louisville hot brown?

Context: A Hot Brown sandwich is an American hot sandwich originally created at the Brown Hotel in Louisville, Kentucky, by Fred K. Schmidt in 1926. It is a variation of traditional Welsh rarebit and was one of two signature sandwiches created by chefs at the Brown Hotel shortly after its founding in 1923. It was created to serve as an alternative to ham and egg late-night dinners.

Ingredients
The Hot Brown is an open-faced sandwich of turkey breast and ham and bacon, covered in creamy Mornay sauce and baked or broiled until the bread is crisp and the sauce begins to brown. Cheddar cheese or American cheese may be added for the sauce. Alternatives for garnishes include tomatoes, mushroom slices, and, very rarely, canned peaches.

Some Hot Browns also include ham with the turkey, and either pimentos or tomatoes over the sauce, and imitation Hot Browns sometimes substitute a commercial cheese sauce instead of the Mornay.

When Fred K. Schmidt created the Hot Brown, its sliced roast turkey was a rarity, as turkey was usually reserved for holiday feasts. The original Hot Brown included the sliced turkey on an open-faced white toast sandwich, with Mornay sauce covering it, with a sprinkling of Parmesan cheese, completed by being oven-broiled until bubbly. Pimento and bacon strips were then added to it. After its debut, it quickly became the choice of 95% of the Brown Hotel's restaurant customers.

The dish is a local specialty and favorite of the Louisville area, and is popular throughout Kentucky. It was long unavailable at its point of origin, as the Brown Hotel was shuttered from 1971 to 1985.

Answer: The Hot Brown is an open faced sandwich that is a local speciality throughout Kentucky.   It was originally served in 1926 at Louisville's Brown Hotel.  The sandwich is a spin on the traditional Welsh Rarebit.  It's turkey breast, served open face on white bread, topped with Mornay sauce and run under the broiler until hot and bubbly.  Some variations include ham with the turkey, as well as pimentos or tomatoes.