In a large skillet over medium heat, melt 2 tablespoons of unsalted butter. Add 2 minced garlic cloves and sauté for about 1 minute until fragrant. Stir in 1 cup of diced lobster and 1 cup of lump crab meat, cooking for an additional 3-4 minutes until the seafood is just warmed through.

In a mixing bowl, combine the sautéed seafood with 8 ounces of softened cream cheese and 1 cup of shredded mozzarella cheese. Mix thoroughly until the ingredients are well combined and creamy.

Bring a large pot of salted water to a rolling boil. Carefully add 20 jumbo pasta shells and cook for 9-11 minutes until they are al dente. Drain and place the shells on a lined baking sheet to cool.

In the same skillet, melt 2 tablespoons of butter. Whisk in 2 tablespoons of all-purpose flour and cook for 2 minutes. Gradually pour in 1 cup of heavy cream while whisking until the sauce thickens. Stir in 1 cup of remaining mozzarella and 1/2 cup of grated Parmesan until melted and smooth.

Preheat your oven to 375°F (190°C). Spread a thin layer of cheese sauce in a 9x13 inch baking dish. Stuff each cooled shell with the seafood filling and place them open 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. Remove the foil and bake for another 10 minutes until the tops are bubbly and golden brown.

Let cool for 5 minutes before serving. Garnish with fresh parsley or extra Parmesan if desired.