In a skillet over medium heat, melt 2 tablespoons of butter and add 2 minced garlic cloves. Sauté until fragrant, about 1-2 minutes. Stir in 1 cup each of lobster and crab meat, cooking for an additional 2-3 minutes until heated through. Remove from heat and let cool.

In a large mixing bowl, combine the sautéed seafood mixture with 8 ounces of cream cheese, 1 cup of shredded mozzarella cheese, and a pinch of salt and pepper. Mix until creamy.

Bring a pot of salted water to a boil and cook the jumbo shells according to package instructions until al dente. Drain shells and let cool slightly.

In the same skillet, melt the remaining 2 tablespoons of butter over medium heat. Sprinkle in 2 tablespoons of flour and whisk until a paste forms, then gradually pour in 1 cup of heavy cream, whisking for 3-4 minutes until thick. Stir in 0.5 cup of Parmesan cheese until melted.

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

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

Let cool for a few minutes before serving. Optionally garnish with extra Parmesan or fresh herbs.