In a large skillet over medium heat, melt 2 tablespoons of butter until bubbly. Add 2 minced garlic cloves and sauté until fragrant, about 1 minute. Gently fold in the chopped lobster and crab meat, cooking for 2-3 minutes until heated through. Remove from heat and set aside to cool while you prepare the filling.

In a mixing bowl, combine the sautéed seafood with 8 ounces of softened cream cheese, 1 cup of shredded mozzarella, and a generous pinch of salt and pepper. Use a spatula to mix them thoroughly until well-combined and creamy.

Bring a large pot of salted water to a boil and cook 16 jumbo pasta shells according to package instructions, typically around 10-12 minutes, until al dente. Drain them well and gently rinse under cool water.

Using the same skillet, melt another 2 tablespoons of butter over medium heat. Whisk in 2 tablespoons of flour and cook for about 1 minute until lightly golden. Gradually add 1 cup of heavy cream and ½ cup of grated Parmesan cheese, whisking constantly until the sauce is smooth and thickened.

Preheat your oven to 375°F (190°C). Spread a thin layer of the cheese sauce across the bottom of a 9x13 inch baking dish. Stuff each pasta shell generously with the seafood filling and place them in the baking dish, seam side up. Pour any remaining cheese sauce over the top.

Cover the baking dish with aluminum foil and place it in the preheated oven. Bake for 20 minutes, then remove the foil and bake for an additional 10 minutes.

Once baked, let your Creamy Seafood Stuffed Shells cool for about 5-10 minutes before serving. Optionally, garnish with extra grated Parmesan or fresh herbs like parsley.