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Lobster Thermidor - A Family Feast

Lobster Thermidor

Lobster Thermidor has chunks of fresh lobster in a thick and creamy sauce with white wine, mushrooms, tarragon, and a splash of cognac. A generous sprinkle of Gruyère cheese on top adds more delicious flavor and a golden color as it is broiled just before serving.

Yield: 4 servings 1x
Prep: 1 hourCook: 1 1/2 hoursTotal: 0 hours


2 lobsters ( approximate 2 1/2-pounds each)


1 small bunch Italian flat-leaf parsley

8 thyme sprigs

3 large tarragon sprigs

2 bay leaves

2 cups white wine

2 whole garlic cloves

1 quart water

2 large whole button mushrooms

1 large yellow onion, peeled and quartered

1 large carrot, rinsed and cut into one-inch pieces

1 large celery stock, cut into one-inch pieces

5 black peppercorns

Cream Sauce/Filling

1 stick butter, divided (8 tablespoons)

8 ounces button mushrooms, sliced

1/2 cup shallots, minced

1/3 cup cognac (could also use brandy)

5 tablespoons all-purpose flour

1 tablespoon Dijon mustard

2 tablespoons grated Parmesan cheese

Pinch cayenne pepper

1 1/2 cups light cream or half and half

Kosher salt and white pepper, as needed after tasting

1/2 cup Gruyere cheese, shredded

2 tablespoons fresh flat leaf Italian parsley, chopped


  1. Tie the parsley, thyme, tarragon, and bay leaves together with twine and place into a large stock pot with the rest of stock ingredients (garlic, wine, water, mushroom, onion, carrot, celery, and peppercorns).
  2. Bring to a boil then simmer partially covered for 30 minutes.
  3. While stock is simmering, prepare the lobsters by laying one on top of the other face to face and tying the tails together with twine. This will stop the tails from curling when cooking.Lobsters In The Freezer for Lobster Thermidor
  4. Place the lobsters into the freezer for 15 minutes to put them to sleep. Or push the blade of a knife through the top of the shell between the eyes and the first joint to kill the lobsters.
  5. Fill a large bowl with ice water to chill the cooked lobsters.
  6. Place the lobsters into the hot stock and bring to a boil and cover. Time ten minutes then using long-handled tongs, remove the lobsters to the ice water to stop the cooking process. Cut twine.
  7. Once they are cool, place a cutting board inside a sheet pan to catch the drips and place the now chilled lobsters on the board. Tear off the legs and add to the stock pot. Pull off the claws and knuckles, pick out the meat and add the empty shells to the stock pot. Bring to a boil and simmer 30 minutes or until the stock has reduced to two cups. Strain and discard all solids.
  8. While the stock finishes cooking, use kitchen shears and carefully cut the tail bottom and top down the middle. Then using a large sharp knife, cut the body in half. You should now have one complete left half and one complete right half.
  9. Pull the tail meat out and pull back the meat that covers the intestinal tract then remove it and discard.
  10. Repeat with the second lobster.
  11. Place all the lobster meat (claws, tail, and knuckles) onto your cutting board and cut all of it into bite sized pieces.
  12. Rinse the empty shell halves, discarding the lobster’s innards. Place the four half shells on a foil lined sheet tray cut side up.
  13. In a large braiser or large skillet, melt half the butter over medium heat and add the cut-up lobster meat and saute a few minutes to finish cooking and to get a nice buttery flavor. Remove to a large bowl using a spider or strainer or large slotted spoon. Do not over cook.
  14. Increase heat to medium high and add the mushrooms and cook 4-5 minutes or until cooked and starting to brown. Also remove these to the bowl with the lobster.
  15. Add the remaining butter and reduce to medium heat and once melted, add the shallots, and cook for two minutes.
  16. Turn off the heat to avoid a flareup and pour in the cognac to deglaze. Turn the heat back on to medium low and once the cognac has evaporated, stir in the flour to make a roux. Cook for two minutes.
  17. Add in just one cup of the stock and stir. Add the Dijon, Parmesan and cayenne and stir.
  18. Stir in the cream, cooked lobster meat and mushrooms and stir until combined.
  19. If too thick, add some of the second cup of lobster stock.
  20. Taste and add kosher or sea salt plus white pepper only if needed.
  21. Remove from heat and divide the filling between the four open shell halves.
  22. Divide the Gruyere cheese over the tops of each then broil until the top has melted and is golden brown.
  23. Sprinkle on the chopped parsley and serve.

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© Author: A Family Feast
Cuisine: French Method: boil, broil