Melt 2 tablespoons of butter in a large skillet over medium heat, add 3 minced garlic cloves, sauté until fragrant. Add 1 cup of lobster meat and 1 cup of crab meat, cook for another 2-3 minutes until heated through.

In a bowl, combine the sautéed seafood with 8 ounces of cream cheese and 1 cup of shredded mozzarella cheese, fold gently until mixed, season with salt and pepper.

Bring salted water to a boil, cook 12 jumbo pasta shells until al dente (10-12 minutes), drain, and cool briefly.

In the skillet, melt 4 tablespoons of butter, whisk in 1/4 cup flour, and gradually add 1 cup of heavy cream and 1/2 cup of grated Parmesan cheese to create a smooth sauce.

Preheat oven to 375°F (190°C). Spread cheese sauce at the bottom of a baking dish, stuff shells with filling, place in dish, and cover with remaining sauce.

Cover with foil and bake for 20 minutes, remove foil, and bake for an additional 10 minutes until golden brown.

Let cool for 5 minutes before serving, garnish with parsley or extra Parmesan.