
Preheat oven to 375°F (190°C). Cook pasta according to package directions. Drain and set aside.
In a large saucepan, melt butter over medium heat. Whisk in flour and cook for 1 minute, stirring constantly.
Gradually whisk in milk and cream until smooth. Bring to a simmer, then reduce heat and simmer for 5 minutes, stirring occasionally.
Remove from heat and stir in Gruyere, cheddar, and Parmesan cheeses until melted and smooth. Season with salt, pepper, and nutmeg.
In a separate skillet, melt 2 tablespoons of butter over medium heat. Add garlic and cook for 1 minute. Add lobster meat and cook for 3-4 minutes, or until heated through.
Combine cooked pasta and cheese sauce in a large bowl. Gently fold in lobster meat.
Pour mixture into a greased baking dish. Sprinkle with toasted breadcrumbs and drizzle with truffle oil (optional).
Bake for 20-25 minutes, or until golden brown and bubbly. Let stand for 5 minutes before serving.