In a large skillet, melt 2 tablespoons of butter over medium heat. Once melted, add 2 minced garlic cloves and sauté until fragrant, about 1 minute. Then, gently fold in the chopped lobster and crab, cooking for an additional 2-3 minutes until just heated through. Remove from heat and set aside to cool.

In a mixing bowl, combine the slightly cooled seafood mixture with 4 ounces of cream cheese, 1 cup of shredded mozzarella, and a pinch of salt and pepper. Mix thoroughly until well blended.

Bring a large pot of salted water to a boil and add the jumbo pasta shells. Cook according to package instructions until al dente, about 8-10 minutes. Drain gently and spread on a clean kitchen towel to cool.

In the same skillet, melt 4 tablespoons of butter over medium heat. Whisk in 2 tablespoons of flour, cooking for about 1 minute until golden. Gradually stir in 1 cup of heavy cream until the sauce thickens, about 3-4 minutes. Add ½ cup of grated Parmesan and ½ cup of shredded mozzarella until smooth.

Preheat oven to 375°F (190°C). Spread a thin layer of sauce at the bottom of a 9x13-inch baking dish. Stuff each shell with the seafood filling and place in the dish. Pour remaining cheese sauce over the top.

Cover the baking dish with aluminum foil and bake for 20 minutes. Remove foil and bake for another 10 minutes until bubbly and golden.

Allow to cool for a few minutes before serving. Garnish with fresh herbs and additional Parmesan.