In a skillet, melt butter over medium heat. Add minced garlic and sauté until fragrant, about 1-2 minutes. Gently stir in the lobster and crab meat, cooking for an additional 2-3 minutes. Set aside to cool.

In a large mixing bowl, combine the sautéed seafood, cream cheese, shredded mozzarella, salt, and pepper. Mix until well blended, ensuring the seafood is evenly distributed.

Boil the jumbo pasta shells according to package instructions until al dente. Drain carefully and let them cool slightly, handling them gently to avoid breaks.

In the same skillet, create a roux by melting butter and whisking in flour until golden. Gradually pour in heavy cream while whisking continuously until smooth. Stir in the remaining mozzarella and Parmesan cheese until the sauce is creamy and well combined.

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

Cover the baking dish with foil and bake for 20 minutes. Remove the foil and continue baking for an additional 10 minutes, or until the sauce is bubbling and slightly golden.

Allow the dish to cool for a few minutes before serving. Garnish with extra grated Parmesan or fresh herbs for a pop of color and flavor.