📝 About This Recipe
Created in 1894 by Marie's restaurant in Paris to honor the premiere of the play 'Thermidor,' this dish remains the pinnacle of French seafood luxury. It features succulent lobster meat bathed in a rich, velvety Cognac-infused Mornay sauce, enriched with heavy cream and finished with a golden Gruyère crust. It is a decadent celebration of dairy and sea, offering a sophisticated balance of earthy mustard, sweet lobster, and buttery indulgence.
🥗 Ingredients
The Lobster
- 2 pieces Live Whole Lobsters (approximately 1.5 lbs each)
- 2 tablespoons Unsalted Butter (melted for brushing)
The Thermidor Sauce
- 4 tablespoons Unsalted Butter (high-quality European style preferred)
- 2 pieces Shallots (minced very finely)
- 3 tablespoons All-purpose Flour
- 1 cup Heavy Cream (at room temperature)
- 1/2 cup Whole Milk (full fat)
- 3 tablespoons Cognac or Brandy (for deglazing)
- 1 tablespoon Dry Sherry (optional but recommended)
- 1 teaspoon Dijon Mustard (smooth, not grainy)
- 1 Egg Yolk (beaten, for thickening and richness)
- 1 pinch Nutmeg (freshly grated)
The Topping & Seasoning
- 1/2 cup Gruyère Cheese (finely grated)
- 2 tablespoons Parmesan Cheese (freshly grated)
- 1 tablespoon Fresh Parsley (finely chopped)
- 1/4 teaspoon Paprika (for color)
- to taste Kosher Salt and White Pepper
👨🍳 Instructions
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1
Bring a large pot of salted water to a rolling boil. Submerge the lobsters and par-boil for 8 minutes; they should be bright red but slightly undercooked. Immediately plunge them into an ice bath to stop the cooking process.
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2
Once cooled, split the lobsters in half lengthwise using a sharp chef's knife. Remove the meat from the tails and claws, discarding the intestinal vein and the 'sand bag' near the head. Save the four half-shells, rinse them thoroughly, and pat dry.
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3
Cut the lobster meat into bite-sized (1-inch) chunks. Set aside in a bowl.
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4
In a medium saucepan over medium heat, melt 4 tablespoons of butter. Add the minced shallots and sauté for 2-3 minutes until translucent and soft, but not browned.
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5
Whisk in the flour to create a roux. Cook for 2 minutes while stirring constantly to remove the raw flour taste, ensuring the mixture remains a pale golden color.
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6
Slowly pour in the Cognac and Sherry. It will bubble vigorously; whisk until the liquid is mostly absorbed by the roux.
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7
Gradually whisk in the milk and heavy cream. Continue to cook over medium-low heat, stirring constantly, until the sauce thickens enough to coat the back of a spoon (about 5-7 minutes).
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8
Remove the pan from heat. Whisk in the Dijon mustard, nutmeg, salt, and white pepper. Temper the egg yolk by whisking a small spoonful of the hot sauce into the yolk, then pour the yolk mixture back into the main sauce, whisking rapidly.
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9
Fold the lobster meat into the cream sauce, along with half of the grated Gruyère and the fresh parsley.
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10
Preheat your broiler to high. Arrange the lobster shells on a baking sheet. Spoon the lobster and sauce mixture generously back into the empty shells.
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11
Sprinkle the remaining Gruyère, Parmesan, and a dusting of paprika over the top of each filled shell.
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12
Place the baking sheet under the broiler for 3-5 minutes, watching closely, until the cheese is bubbling and has developed deep golden-brown spots.
💡 Chef's Tips
Always use fresh, high-quality heavy cream; lower fat substitutes will break under the broiler. When tempering the egg yolk, go slowly to prevent the yolk from scrambling in the hot sauce. If the sauce feels too thick, add a tablespoon of lobster stock or clam juice to loosen it. Don't overcook the lobster during the initial boil; the broiler will finish the cooking to ensure a tender texture. Use white pepper instead of black to maintain the pristine, creamy aesthetic of the sauce.
🍽️ Serving Suggestions
Serve with a side of buttery Haricots Verts (French green beans) and toasted baguette slices. Pair with a chilled bottle of Meursault or a high-quality Oaked Chardonnay. A simple watercress salad with a lemon vinaigrette provides a crisp contrast to the rich dairy. For a truly grand presentation, serve on a bed of rock salt garnished with lemon wedges and fresh chervil.