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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.
What is Lobster Thermidor?
It’s a French dish made with chunks of fresh lobster in a rich and creamy mushroom sauce with white wine, tarragon, and cognac added – lending this dish a very distinctive flavor. The sauce is spooned into lobster tails, then topped with Gruyère cheese and broiled until golden brown and bubbly.
Lobster Thermidor Origins
While definitely of French origins, there are several different stories that credit chefs at different restaurants in Paris for creating this dish in the late 1800’s. The most common story claims that Lobster Thermidor was created for the premierw of ‘Thermidor’ – a play by Victorien Sardou – that was named after the month of heat, called Thermidor (July 19th-August 17th), in the French Republican calendar.
Preparation Options
There are two ways to make Lobster Thermidor: Quick and easy, or 100% from scratch.
A quick and easy recipe would use a boxed seafood stock and pre-cooked lobster meat (which can be very expensive to buy) and baked in ramekins for serving. (We do note some options to make preparation easier below.)
When Lobster Thermidor is made from scratch – which is what we did for our recipe today – you’ll make a homemade seafood stock, cook the fresh live lobsters in that stock, and the final dish is presented in the lobster shells.
This really isn’t a difficult recipe (even from scratch) but it does take some time and a few tips and tricks – but your time will be rewarded with a rich and delicious meal that your dinner guests will talk about for months to come!
Why you’ll love Lobster Thermidor
- The combination of flavors including the lobster, tarragon, Cognac, and Gruyère cheese are truly wonderful together.
- It’s rich, delicious, and purely decadent comfort food.
- This recipe is the perfect option for a special meal or intimate holiday dinner party.
Key Ingredients & Substitutions
- Lobster – Buy live and kicking lobsters, about 2 ½ pounds each. These will be cooked in a homemade lobster stock and the shells will be used for the final serving presentation. (Alternatively, you could buy 1½ pounds of cooked lobster meat and 1 quart of boxed stock if you want to take a shortcut.)
- Stock Ingredients – White wine, water, whole button mushrooms, large yellow onion, fresh garlic, carrot, celery, fresh parsley, bay leaves, fresh thyme, fresh tarragon, and whole black peppercorns.
- Vegetables for the Cream Sauce – Sliced button mushrooms and fresh minced shallots.
- Cream Sauce Ingredients – Butter, all-purpose flour, cognac, stock from above, cream, Dijon mustard, cayenne pepper, and Parmesan cheese.
- Topping – Gruyère Swiss cheese and fresh, flat-leaf Italian parsley.
Special Tools Needed
- Large Soup Pot – To make the stock and cook the lobsters.
- Butcher’s Twine
- Large Bowl – For ice water to cool the cooked lobsters.
- Cutting Board and Large Sharp Kitchen Knife
- Large Rimmed Sheet Tray – This should be about the same size/slightly larger than your cutting board.
- Kitchen Scissors
- Large Braiser or large heavy skillet.
- Various Measuring Cups and Spoons
- Large Tongs
- Strainer
- Long Wooden Spoon
- 2 Sheet Trays
- Large and Long Spatula such as a fish turner/spatula like this.
- Lobster Cracker and Pick
- Another Bowl – To hold the picked lobster meat.
How do I make Lobster Thermidor?
- Make the stock by placing all stock ingredients into a large stock pot. Simmer for 30 minutes.
- While stock cooks, position two live lobsters together face to face and tie their tails to each other with butcher’s twine. This will keep the tails from curling while cooked. (See photo in the recipe card below showing this step.)
- Place tied lobsters in the freezer for 15 minutes to put them to sleep. Alternatively, you could run a sharp knife down through the top shell between the eyes and the first joint to kill them before cooking. (Totally understand if you don’t have the heart to do this.)
- Plunge the lobsters into the boiling stock, cover, and time ten minutes. After ten minutes, remove the partially cooked lobsters to a large bowl of ice water to stop the cooking process.
- Remove lobsters from the ice water bath and place on a cutting board over a sheet tray to catch any drips. Pull legs off and place in the stock pot. Pull claws and knuckles off, pick out and save meat in a bowl, then put empty claws in the stock pot.
- Use kitchen scissors and cut tail in half down the middle (cut one side, flip and cut the other), then take a long sharp knife and cut lobster body in half the long way, leaving tail shell connected. Repeat for second lobster. You will have two long halves (half a body, head, and tail, a left and a right half from each lobster). Rinse the shells out, discarding the lobster innards. Place the four empty halves on a foil lined sheet tray, cut side up. (If your shells shatter apart while doing this step, don’t worry – bake your Lobster Thermidor in individual baking dishes instead.)
- Pick out the tail meat and add to the bowl with the claw meat. Pull out the long tract that resides in the tail portion and discard the tract.
- Pick meat from knuckles and add to the bowl with claw and tail meat. Then put knuckle shells into the stock pot.
- Cut all reserved lobster meat into bite-sized pieces.
- Bring the stock to a boil, then simmer for 30 more minutes or until the liquid has reduced to two cups. Strain and discard the solids.
- Make the cream sauce by sautéing the lobster meat in butter. Remove to a bowl. Add mushrooms and cook, then add to the bowl with the lobster. Add more butter and shallots and cook for two minutes, then add cognac to the pan to deglaze.
- Add the flour to make a roux and cook over medium low for two minutes, then stir in one cup of stock. Add Dijon, cayenne, and Parmesan.
- Add cream, cooked lobster meat, and cooked mushrooms to finish the filling. Stir, taste and season with kosher salt and white pepper if needed. We added a little salt and pepper. If mixture is too thick, thin down with some of the second cup of stock.
- Divide the filling evenly between the four lobster shells halves and cover each with the shredded Gruyère Swiss cheese. Broil until golden on top.
- Sprinkle chopped parsley over each portion and serve. (Note: We served our Lobster Thermidor on a bed of curly lettuce.)
Tips & Tricks
Cooking the stock and the lobsters can be done a day in advance – in fact, we recommend doing so since the process can be messy cracking and cleaning the lobster shells.
If you get the stock and shells done the day before, you will have a chance to clean up and start fresh the next day. Then, make the sauce, stuff the lobster shells, and broil for your dinner guests.
Frequently Asked Questions
- Can I make Lobster Thermidor ahead of time? Yes – we actually recommend that you cook the lobster and make the stock the day before you plan to serve this dish. Prepare the sauce and assemble the lobster shells the day you plan to serve.
- How do I store leftovers? Store refrigerated for up to two days.
- How do I reheat leftovers? Best to reheat the filled lobster shells in the oven until the filling is hot. Or, you can scoop out the cream sauce/filling and gently microwave to warm through. Avoid overheating – the lobster will get tough and rubbery.
- Can I freeze? No, the lobster meat will become tough.
Additional Serving Suggestion
As you prepare Lobster Thermidor, if you struggle with keeping the lobster shells intact when you remove the meat, please don’t panic!
You can prepare this recipe and serve it in individual serving dishes as shown below. It will still taste the same and have a wonderful dinner presentation.
You might like these other Lobster Recipes:
Click here for more delicious Seafood Recipes!
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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.
Ingredients
2 lobsters ( approximate 2 1/2-pounds each)
Stock
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
Instructions
- 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).
- Bring to a boil then simmer partially covered for 30 minutes.
- 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.
- 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.
- Fill a large bowl with ice water to chill the cooked lobsters.
- 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.
- 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.
- 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.
- Pull the tail meat out and pull back the meat that covers the intestinal tract then remove it and discard.
- Repeat with the second lobster.
- Place all the lobster meat (claws, tail, and knuckles) onto your cutting board and cut all of it into bite sized pieces.
- Rinse the empty shell halves, discarding the lobster’s innards. Place the four half shells on a foil lined sheet tray cut side up.
- 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.
- 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.
- Add the remaining butter and reduce to medium heat and once melted, add the shallots, and cook for two minutes.
- 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.
- Add in just one cup of the stock and stir. Add the Dijon, Parmesan and cayenne and stir.
- Stir in the cream, cooked lobster meat and mushrooms and stir until combined.
- If too thick, add some of the second cup of lobster stock.
- Taste and add kosher or sea salt plus white pepper only if needed.
- Remove from heat and divide the filling between the four open shell halves.
- Divide the Gruyere cheese over the tops of each then broil until the top has melted and is golden brown.
- Sprinkle on the chopped parsley and serve.
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