Pepperoni Pizza Casserole

1 pound ground beef

1 (8 ounce) package uncooked egg noodles

1 (16 ounce) jar spaghetti sauce, or as needed

1 (2.25 ounce) can sliced black olives, drained

1 (2.5 ounce) can sliced mushrooms, drained

1 (8 ounce) package sliced pepperoni, coarsely chopped

20 ounces shredded mozzarella cheese, divided

Preheat oven to 375 degrees F (190 degrees C).

Cook the ground beef in a skillet over medium heat until no longer pink, breaking the meat apart into crumbles as it cooks, about 10 minutes.

Bring a large pot of lightly salted water to a rolling boil. Cook the egg noodles in the boiling water until cooked through yet slightly firm, about 5 minutes; drain.

Mix the noodles with the cooked ground beef, spaghetti sauce, black olives, mushrooms, pepperoni, and 1/2 of the mozzarella cheese in a large mixing bowl. Spoon the mixture into a 9x13-inch baking dish and top with remaining cheese. Cover the dish with foil.

Bake in the preheated oven until the casserole is bubbling, 30 to 45 minutes.