In a skillet over medium heat, melt 2 tablespoons of butter and add minced garlic. Sauté until fragrant, about 1-2 minutes.

Stir in lobster and crab meat, cooking for an additional 2-3 minutes until heated through. Remove from heat and cool.

In a large bowl, combine sautéed seafood, cream cheese, shredded mozzarella, salt, and pepper. Mix until creamy.

Cook the jumbo shells in salted boiling water for 12-15 minutes until al dente. Drain and cool on a towel.

In the same skillet, melt remaining butter and whisk in flour. Gradually add heavy cream, whisking until sauce thickens.

Stir in grated Parmesan cheese until melted and smooth.

Preheat oven to 375°F (190°C). Spread some sauce on the bottom of a greased baking dish, stuff shells with filling, and arrange in dish.

Pour remaining sauce over stuffed shells, cover with foil, and bake for 20 minutes. Remove foil and bake for another 10 minutes.

Let cool for a few minutes before serving. Garnish if desired.