Preheat oven to 350 degrees F (175 degrees C).

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. Let cool for 3 to 5 minutes before serving.