In a skillet, melt 2 tablespoons of butter over medium heat. Add minced garlic and sauté for about 1 minute until fragrant and golden. Gently fold in the lobster and crab meat, cooking for 2-3 minutes until heated through.

In a large mixing bowl, combine the sautéed seafood with cream cheese, shredded mozzarella, salt, and pepper. Blend until smooth and creamy.

Bring a large pot of salted water to a rolling boil, then add your jumbo pasta shells. Cook until al dente (usually about 8-10 minutes). Drain and rinse under cold water.

In the same skillet, melt the remaining 2 tablespoons of butter over medium-low heat. Whisk in the flour and cook until golden, about 1-2 minutes. Gradually stir in the heavy cream and Parmesan cheese, whisking until the sauce is velvety, about 3-4 minutes.

Preheat your oven to 375°F (190°C). Spread a layer of the creamy sauce in the bottom of a baking dish. Stuff each pasta shell with the seafood filling and place them seam side up in the dish. Pour the remaining sauce over the stuffed shells.

Cover the baking dish with aluminum foil and bake for 20 minutes, then remove the foil and bake for an additional 10 minutes, or until bubbly and golden brown.

Allow to cool for a few minutes. Garnish with additional Parmesan cheese and serve warm.