Preheat the oven to 375°F.

Spray a 9x13-inch square baking dish with nonstick cooking spray. Set aside.

Bring a large pot of water to a boil. Add a generous pinch of salt. Once boiling, add the ziti to the water. Cook, stirring occasionally, until the pasta is al dente, 9-10 minutes. Drain the pasta in a large colander, and rinse thoroughly with cold water. While the pasta cooks, prepare the sauce.

In a large sauce pan over medium heat, melt the butter. Once melted, add the flour and whisk to form a paste. Continue whisking until the paste thickens, turns slightly golden, and begins to smell toasty, 1-2 minutes.

Slowly stream the milk into the pot and continue to whisk. Pour in the heavy cream. Cook the mixture, whisking steadily, until it begins to thicken and bubble, 4-5 minutes.

Once bubbling, turn off the heat. Add the cream cheese, Parmesan, mozzarella, salt, black pepper, and garlic powder to the pot. Whisk slowly until the cheese is completely melted and the sauce is smooth.

Return the drained ziti to the pot. Add the sauce and stir with a rubber spatula until it is thoroughly coated.

Transfer the pasta to the prepared baking dish. Sprinkle the additional mozzarella cheese in an even layer over the top.

Bake the ziti on middle rack of oven until edges are bubbling and cheese is slightly golden on top, 25-28 minutes.

Check to see that ziti is done. Remove from oven or add time as needed.

Allow it to rest for 15-20 minutes before serving.