Preheat oven to 375°. Cook noodles according to package directions; drain. In a large bowl, combine noodles and 3/4 cup pizza sauce. Transfer to a greased 13x9-in. baking dish. Top with remaining pizza sauce., Layer with the mushrooms, olives and pepperoni. Sprinkle with cheese. Bake, uncovered, until heated through and cheese is melted, 15-18 minutes.