Lobster Thermidor is a rich and elegant French dish featuring tender lobster meat in a creamy, Cognac-infused sauce, nestled back into the shell, topped with Gruyere, and baked until golden and bubbling.

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About This Recipe
Lobster Thermidor is the epitome of French decadence that combines tender, succulent lobster meat with a luxurious, Cognac-infused cream sauce. The mixture is then nestled back into the lobster shells, generously topped with nutty Gruyere cheese, and baked until golden and bubbling.
This updated version remains true to Julia Child’s original vision but simplifies the process without sacrificing any of the rich, buttery flavors. This classic French dish boasts a rich, velvety texture with deep, savory flavors, making it the perfect indulgence for a special occasion.
If you're looking to explore more classic French recipes, try Julia Child’s Cheese Soufflé or Julia Child’s Sole Meuniere.
🦞 Where to find Whole Lobsters
For the best quality lobster, I highly recommend ordering from ShopLobster. Whether you're looking for Maine lobster delivery, fresh lobster tails on sale, or simply want to order lobster online, they provide top-notch seafood directly to your door! Thank you, ShopLobster for providing such beautiful lobsters for this classic recipe!
📍 Lobster Thermidor Updates
I originally posted this recipe in 2013 and made sure to follow Julia Child's exact recipe. Over the years, I like to update recipes, give them a facelift and see if they can be easier for the homecook. Here are the updates I've made from Julia's original recipe while still keeping the traditional lobster thermidor.
- Lobster stock: While homemade lobster stock is still made (might as well if you have whole lobsters), use any aromatics that you have, such as onions, carrots, and herbs. You can also use a homemade seafood stock or store-bought seafood stock.
- One-pan method: Instead of using three separate pans (one to sauté the lobster meat in butter, one to sauté the mushrooms, and one to make the cream sauce), this updated version condenses everything into a single pan, creating a rich, flavorful sauce with less hassle.
- No egg tempering: Julia’s original recipe thickens the sauce with egg yolks, but after testing, I found this step unnecessary. The thick béchamel, cheese, heavy cream, and butter provide all the richness needed.
📋 Ingredients
- Lobster: The star of the dish! Whole live lobsters yield the best flavor, but you can also use lobster tails for a simpler approach. Boiling the lobsters ensures tender, juicy meat.
- Lobster Stock: This homemade stock adds incredible depth. However, you can substitute it with homemade seafood stock or high-quality store-bought seafood stock.
- Cognac: A classic addition that enhances the sauce with a rich, slightly sweet complexity. Brandy is a great alternative if you don’t have Cognac on hand.
- Heavy Cream & Butter: These ingredients provide a silky, luxurious texture to the sauce. They replace the need for tempering egg yolks, simplifying the preparation.
- Gruyere Cheese: Essential for that golden, bubbly topping. Parmesan can also be added for extra depth.
- Dijon Mustard: This adds a tangy sharpness that balances the richness of the sauce.
- Mushrooms & Shallots: Sautéed mushrooms and shallots add an earthy, aromatic element to complement the lobster’s sweetness.
- Fresh Herbs: Thyme and parsley bring brightness and contrast to the dish’s rich flavors.
See recipe card for full information on ingredients and quantities.
🍋 Substitutions and Variations
- Lobster Tails Instead of Whole Lobster: If handling whole lobsters feels intimidating, you can use lobster tails instead. They’re easier to prepare and still deliver that rich, buttery flavor.
- Seafood Stock Alternative: Instead of lobster stock, you can use a homemade seafood stock or a good quality store-bought stock.
- No Cognac?: If Cognac isn’t available, brandy or sherry make a great substitute with similar depth and warmth.
- Cheese Variations: While Gruyere is traditional, you can mix in Parmesan or even a bit of Swiss cheese for added complexity.
- No Mushrooms? You can omit them entirely or replace them with finely diced leeks for a milder, subtly sweet flavor.
⏲️ Instructions: How to make Lobster Thermidor
Steaming the Lobsters
Add Aromatics: Fill a large pot with water, white wine, onion, carrots, celery, parsley, and thyme. Stir to combine.
Cook the Lobsters: Add lobsters and cook for 20 minutes, until they turn bright red. Then remove and place on ice. Simmer the stock for 10 minutes, then strain and reserve.
Prep the Lobster Meat
Split the Lobsters: Cut the cooked lobsters in half and remove the meat from the tail and claws. Reserve the shells for later use.
Prep the Lobster Meat: Chop up all of the lobster meat into ½ inch pieces.
Lobster Thermidor Sauce
Saute the Mushrooms: Heat a wide skillet over medium heat and add olive oil butter. Sauté the mushrooms until deeply browned, about 9-10 minutes. Add shallot and thyme and cook for another 2 minutes.
Deglaze with Cognac: Carefully pour in the Cognac, cooking off the alcohol. For a dramatic effect, carefully ignite the Cognac, allowing the flames to subside naturally. Season with salt and pepper.
Thicken the Sauce: Add butter and let it melt, then stir in flour and cook for 1-2 minutes. Pour in stock and bring to a strong simmer for 3-5 minutes, until thickened. Add the Dijon mustard, cayenne, and Parmesan and stir together.
Add the Lobster: Reduce the heat to low and stir in the heavy cream. Simmer for another 2-3 minutes then add the chopped lobster meat.
Assemble the Lobster Thermidor
Fill the Lobster Shells: Preheat oven to 425°F and place the lobster shells on a baking sheet and divide the mixture between the shells.
Bake the Lobster Thermidor: Sprinkle Gruyere cheese over the top of each lobster half. Bake for 5-7 minutes, until cheese has melted.
📍 Recipe Tips
- Chill the lobsters in the freezer for 30-45 minutes before cooking to numb them, making it more humane to dispatch them.
- Use a sharp knife to quickly and firmly split the lobster’s head to ensure an instant, humane dispatch.
- Immediately place the cooked lobsters into an ice bath to stop the cooking process.
- For a deeper, more concentrated flavor, let the lobster stock reduce slightly before using it in the sauce.
- To achieve a beautifully browned cheese topping, finish the Lobster Thermidor under the broiler for 2-3 minutes, watching closely.
🍽️ What to Serve with Lobster Thermidor
Lobster Thermidor is rich and indulgent, so it pairs well with light, complementary side dishes. Here are some great options:
- Crusty French Bread: Perfect for soaking up the creamy sauce.
- Simple Green Salad: A crisp Caesar salad would be a fantastic addition and helps balance the richness.
- Garlic Butter Asparagus: Adds a crisp, flavorful contrast.
- Chilled White Wine: A crisp Chardonnay or Sauvignon Blanc complements the flavors beautifully.
More Shellfish Recipes
Lobster Thermidor Recipe with Cognac
Equipment
Ingredients
Lobster Stock Ingredients
- 2 cups water
- 1 cup white wine
- 1 onion cut in half
- 2-3 carrots cut in half
- 2 celery stalks cut in half
- Small bunch of fresh parsley
- Small bunch of fresh thyme
- 4 whole lobsters about 1 ¼-1 ½ pounds each (totaling 5-6 pounds)
Thermidor Sauce Ingredients
- Cooked lobster meat
- 2 tablespoons olive oil
- 2 tablespoons butter + 4 tablespoons butter separated
- 1 pint button or cremini mushrooms sliced
- 1 shallot diced
- 2 tablespoons fresh thyme leaves roughly chopped
- ¼ cup Cognac
- ½ teaspoon Kosher salt
- Ground black pepper
- ¼ cup flour
- 2 cups lobster stock
- 1 tablespoon Dijon mustard
- ½ cup grated Parmesan
- ½ cup cream
- Pinch of cayenne
- ½ cup grated Gruyere cheese
For Serving
- Chopped parsley for garnish
- Lemon wedges for serving
Instructions
Steaming the Lobsters
- Fill a large pot with water, white wine, onion, carrots, celery, parsley, and thyme. Stir to combine.
- To humanely kill the lobsters, place them in the freezer for 30-45 minutes to numb them. Then, using a sharp chef’s knife, quickly and firmly insert the tip into the cross-section on the lobster’s head, just behind the eyes, pressing down to split the head in half.
- Immediately place the lobsters into the pot and bring to a gentle simmer. Cook for about 20 minutes, until they turn bright red.
- Remove the lobsters and place them in an ice bath to stop the cooking process.
- Continue simmering the lobster stock for another 10-15 minutes to reduce. Strain the stock, discarding the aromatics, and set the liquid aside.
Prepping the Cooked Lobsters
- Split the lobsters in half lengthwise, keeping the shells intact.
- Remove the meat from the tails and claws, cutting it into ½-inch pieces.
- Clean the lobster shells and set them aside for later use.
Making the Thermidor Sauce
- Heat a wide skillet over medium heat and add olive oil and 2 tablespoons of butter. Sauté the mushrooms until deeply browned, about 9-10 minutes.
- Add diced shallot and thyme and cook for another 2 minutes.
- Carefully pour in the Cognac to deglaze the pan, cooking off the alcohol. For a dramatic effect, you can carefully ignite the Cognac, allowing the flames to subside naturally. Season with salt and pepper.
- Add the remaining 4 tablespoons of butter and let it melt. Stir in the flour and cook for 1-2 minutes until no raw flour remains.
- Pour in the lobster stock and stir. Bring to a strong simmer for 3-5 minutes, until thickened and able to coat the back of a spoon. Stir in Dijon mustard, cayenne, and Parmesan.
- Reduce the heat to low and add the cream, simmering for another 2-3 minutes.
- Gently fold in the chopped lobster meat, being careful not to break it up.
Assembling the Lobster Thermidor
- Preheat oven to 425°F.
- Place the cleaned lobster shells on a baking sheet and evenly divide the creamy lobster mixture into the shells, being careful not to overfill.
- Sprinkle Gruyere cheese over the top of each lobster half.
- Bake for 5-7 minutes, until the cheese is melted. For a golden-brown finish, broil for an additional 2-3 minutes, watching closely.
- Let cool slightly, then garnish with chopped parsley and serve with lemon wedges.
Notes
- Chill the lobsters in the freezer for 30-45 minutes before cooking to numb them, making it more humane to dispatch them.
- Use a sharp knife to quickly and firmly split the lobster’s head to ensure an instant, humane dispatch.
- Immediately place the cooked lobsters into an ice bath to stop the cooking process.
- For extra flavor, let the lobster stock reduce slightly before using it in the sauce.
- To achieve a beautifully browned cheese topping, finish the Lobster Thermidor under the broiler for 2-3 minutes, watching closely.