Cook the spaghetti according to the package directions, then drain and set aside to cool.
Preheat the oven to 350 degrees F. Generously spray a 10-inch springform pan or deep-dish pie pan with cooking spray.
In a bowl, mix the cooked spaghetti, Parmesan, milk, garlic powder, salt, eggs and 1 cup mozzarella cheese.
Spoon the mixture into the prepared pan and press it down into the pan. Pour on the pizza sauce. Add the preferred toppings and sprinkle with the remaining cup mozzarella. Place the pan on a rimmed baking sheet and bake until golden and bubbly, 35 to 40 minutes.