Creating Lobster Thermidor involves several straightforward steps. Follow these instructions carefully for a remarkable result:

1. Boil the Lobsters: Place the lobsters in a large pot of boiling water. Cook them for about 8-10 minutes until they turn bright red. Remove and cool.
2. Remove the Meat: Once cool, carefully split the lobsters in half and remove the meat, reserving the shells. Chop the lobster meat into bite-sized pieces.
3. Prepare Sauce: In a saucepan, melt the butter over medium heat. Once melted, stir in the flour to create a roux, cooking for about 2 minutes until golden.
4. Add Cream and Wine: Gradually whisk in the heavy cream and white wine, stirring continuously until the sauce thickens (about 5-7 minutes).
5. Combine with Lobster: Mix in the lobster meat, mustard, lemon juice, salt, pepper, and cayenne pepper into the sauce, ensuring even coating.
6. Prepare for Baking: Preheat your oven to 400°F (200°C). Spoon the lobster mixture back into the reserved lobster shells and place them on a baking tray.
7. Top with Cheese: Generously sprinkle Gruyère cheese over the filled lobster shells.
8. Bake: Place the tray in the preheated oven and bake for 10-15 minutes until the cheese is bubbly and golden brown.
9. Garnish and Serve: Remove from the oven, garnish with chopped parsley, and serve hot.

Following these steps will yield an incredible Lobster Thermidor that will tantalize your taste buds and impress your guests.