Pizzaghetti is a Québec dish.
It is pizza baked with its regular ingredients on it, then topped with plain, cooked spaghetti (usually covering the pizza entirely.)
Then the spaghetti is topped with a sauce (usually a meat or plain tomato sauce), then served.
It may be accompanied by garlic bread.
The spaghetti is sometimes served on the side, though purists insist it should be on top the pizza.
In America, a pizzaghetti is less true to its name. It is a plate of pizza, with pepperoni, sausage, sliced mushrooms, sliced onion and sliced green pepper on it, sprinkled with mozzarella cheese.