Preheat your oven to 375°F and coat a 9×13-inch baking dish with non-stick spray. This helps heat the dish evenly and keeps the pasta from sticking.
Boil penne according to package instructions, then drain and set aside. Salting the water adds flavor to every bite.
In a large skillet over medium-low heat, add butter and heavy cream. Whisk until the butter melts and the mixture is smooth and combined.
Stir in garlic, garlic powder, Italian seasoning, salt, and pepper. Whisk so the garlic softens and the spices infuse the sauce.
Bring the skillet to a gentle simmer, whisking constantly. Cook for 3 to 4 minutes until the sauce thickens enough to coat the back of a spoon.
Mix in Parmesan until it melts fully, then remove the pan from heat. The cheese creates a creamy texture and a nutty flavor.
Toss the drained pasta and shrimp with the sauce, then spread it in your prepared dish. Top with mozzarella and bake, uncovered, for 20 minutes until bubbly and the cheese turns lightly golden. Serve immediately.