Step 1: Preheat your oven to 375°F (190°C). Lightly grease a 9×13 inch baking dish. Bring a large pot of salted water to a rolling boil. Add the pasta and cook according to package directions until al dente. Drain well and toss with 2 tablespoons of olive oil to prevent sticking. Set aside.
Step 2: In a large, heavy-bottomed pot or Dutch oven, melt 6 tablespoons of unsalted butter over medium heat. Add the flour and cook, whisking constantly, for 2-3 minutes to create a roux. Do not let it brown too much. It should be light golden.
Step 3: Gradually whisk in the warm milk, a little at a time, ensuring no lumps form. Continue to whisk until the sauce is smooth and thickened, about 5-7 minutes. Bring to a gentle simmer, stirring constantly, then reduce heat to low.
Step 4: Remove the pot from the heat. Stir in the Dijon mustard, cayenne pepper (if using), and nutmeg. Season with salt and white pepper to taste. Begin adding the shredded cheddar and Gruyère cheeses in batches, stirring until each batch is completely melted and incorporated before adding more. Stir in 1/2 cup of the grated Parmesan until melted and smooth.
Step 5: Add the cooked pasta and the chopped lobster meat to the cheese sauce. Gently fold everything together until the pasta and lobster are evenly coated. Taste and adjust seasoning if necessary for this gourmet lobster mac and cheese bake recipe.
Step 6: Pour the mixture into the prepared baking dish. In a small bowl, melt the remaining 2 tablespoons of butter. Toss the panko breadcrumbs with the melted butter and an additional 1/4 cup of grated Parmesan cheese. Sprinkle the breadcrumb mixture evenly over the top of the mac and cheese.
Step 7: Bake for 25-35 minutes, or until the top is golden brown and the cheese sauce is bubbly around the edges. Let the gourmet lobster mac and cheese bake recipe rest for 5-10 minutes before serving to allow the sauce to set slightly. Serve hot and enjoy!