Before I explain why I had asked that question, I might as well talk about the background and history of Lobster Thermidor. The recipe for Lobster Thermidor was created around 1880 by the famous French chef Auguste Escoffier at a French restaurant called Maison Maire.
The seafood dish consisted of a creamy mixture of cooked lobster meat, egg yolks, and brandy – usually cognac – that is stuffed into a lobster shell. Lobster Thermidor can also be served with an oven-browned cheese crust, usually Gruyère. Once all of this has been prepared, the dish is topped with a sauce made from mustard (usually powdered).
The Maison Maire restaurant, where Escoffier created the dish, was located near a theater called the Comédie-Française. In January 1891, a play written by Victorien Sardou called “Thermidor” opened at the Comédie-Française. It took its name from a summer month in the French Republican Calendar, during which the Thermidorian Reaction occurred, overthrowing Robespierre and ending the Reign of Terror. The owner of the Maison Maire, Monsieur Paillard, renamed Escoffer’s dish “Lobster Thermidor” after Sardou’s play became a hit. However, due to the expensive and extensive preparation involved in Lobster Thermidor, its appearance on restaurant menus have declined over the years and is now usually prepared for special occasions.
Below is a recipe for Lobster Thermidor from the Epicurious website:
2 (1 1/2-lb) live lobsters
1/2 stick (1/4 cup) unsalted butter
1/4 lb mushrooms, trimmed and thinly sliced
1/2 teaspoon paprika
1/8 teaspoon salt
1/4 teaspoon black pepper
2 tablespoons medium-dry Sherry
1 cup heavy cream, scalded
2 large egg yolks
Plunge lobsters headfirst into an 8-quart pot of boiling salted water*. Loosely cover pot and cook lobsters over moderately high heat 9 minutes from time they enter water, then transfer with tongs to sink to cool.
When lobsters are cool enough to handle, twist off claws and crack them, then remove meat. Halve lobsters lengthwise with kitchen shears, beginning from tail end, then remove tail meat, reserving shells. Cut all lobster meat into 1/4-inch pieces. Discard any remaining lobster innards, then rinse and dry shells.
Heat butter in a 2-quart heavy saucepan over moderate heat until foam subsides, then cook mushrooms, stirring, until liquid that mushrooms give off is evaporated and they begin to brown, about 5 minutes. Add lobster meat, paprika, salt, and pepper and reduce heat to low. Cook, shaking pan gently, 1 minute. Add 1 tablespoon Sherry and 1/2 cup hot cream and simmer 5 minutes.
Whisk together yolks and remaining tablespoon Sherry in a small bowl. Slowly pour remaining 1/2 cup hot cream into yolks, whisking constantly, and transfer to a small heavy saucepan. Cook custard over very low heat, whisking constantly, until it is slightly thickened and registers 160°F on an instant-read thermometer. Add custard to lobster mixture, stirring gently.
Arrange lobster shells, cut sides up, in a shallow baking pan and spoon lobster with some of sauce into shells. Broil lobsters 6 inches from heat until golden brown, 4 to 5 minutes. Serve remaining sauce on the side.
When salting water for cooking, use 1 tablespoon salt for every 4 quarts water.