Bring a large pot of lightly salted water to a boil. Cook elbow macaroni in the boiling water, stirring occasionally, until cooked through but firm to the bite, 8 minutes.
Drain.
Cook and stir ground beef in a skillet over medium heat until meat is crumbly and browned, about 10 minutes; drain excess grease.
Mix cooked ground beef, macaroni, pizza sauce, tomato sauce, and mushrooms in a bowl.
Layer half the macaroni mixture into a 9x12-inch baking dish; top with 1/2 the mozzarella cheese.
Layer remaining macaroni mixture over the top; sprinkle remaining mozzarella cheese over macaroni mixture. Cover dish with aluminum foil.
Bake in the preheated oven until cheese has melted and casserole is bubbling, about 35 minutes.
