Sauté minced garlic in melted butter over medium heat until fragrant, about 1 minute.

Add in the lobster and crab, cooking for 2-3 minutes until just heated through. Set aside to cool slightly.

In a mixing bowl, combine sautéed seafood with cream cheese and half of the shredded mozzarella. Season with salt and pepper, and mix well.

Bring a large pot of salted water to boil. Cook jumbo pasta shells according to package instructions until al dente, then drain and cool slightly.

In the same skillet, melt the remaining butter. Whisk in flour and cook for about 1 minute to make a roux. Gradually add heavy cream, whisking until smooth.

Stir in the rest of the mozzarella and Parmesan until fully melted.

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

Cover and bake for 20 minutes. Remove foil and bake for an additional 10 minutes until bubbly and golden brown.

Allow to cool for a few minutes before serving. Garnish with extra Parmesan or fresh herbs.