Preheat the oven to 375°F (190°C).
Bring a large pot of salted water to a boil and cook the pasta until al dente, about 1–2 minutes less than the package directions.
Drain the pasta and set aside.
Melt the butter in a medium saucepan over medium heat.
Whisk in the flour and cook for 1 minute.
Gradually whisk in the milk and heavy cream until smooth.
Cook for 3–5 minutes, stirring constantly, until the sauce begins to thicken.
Add the garlic powder, onion powder, Italian seasoning, salt, and black pepper.
Reduce the heat to low and stir in the mozzarella, Fontina, and Parmesan until melted and smooth.
Fold the cooked pasta into the cheese sauce until evenly coated.
Transfer the mixture to a greased 9×13-inch baking dish.
Mix the breadcrumbs, Parmesan, and melted butter, then sprinkle evenly over the pasta.
Bake for 20–25 minutes, or until the topping is golden brown and the cheese is bubbling.
Remove from the oven and let the mac and cheese rest for 10 minutes before serving to allow the sauce to set.