Preheat the oven to 350°F (175°C).
Cook the penne pasta according to package instructions until al dente. Drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant.
Add the shrimp to the skillet and cook for about 3-4 minutes until they turn pink. Remove from heat and gently fold in the crab meat.
In a large mixing bowl, combine the heavy cream, Parmesan cheese, Italian seasoning, salt, and pepper. Mix until well blended.
Add the cooked pasta to the cream mixture, and then fold in the shrimp and crab. Stir together until everything is evenly coated.
Transfer the mixture to a greased baking dish.
Sprinkle the shredded mozzarella cheese evenly over the top, followed by the breadcrumbs for extra crunch.
Bake in the preheated oven for 25-30 minutes or until the cheese is melted and bubbly, and the top is golden brown.
Remove from the oven and let it cool for 5 minutes before serving.