Bring a large pot of salted water to a boil. Add pasta and cook until al dente; drain and set aside.
Preheat oven to 375 degrees.
In a large bowl, mix pasta, ricotta cheese, half of the mozzarella cheese, egg, and half of the jar of spaghetti sauce.
Lightly grease a 9x13 pan and spoon in pasta mixture. Top with remaining spaghetti sauce, followed by the parmesan cheese and the rest of the mozzarella.
Bake for 25 minutes, then turn on the broiler. Cook 5 minutes more to get that nice, browned, cheesy crust on top.