1 (16 ounce) package spaghetti with mushrooms
2 cups shredded Cheddar cheese
1 (16 ounce) can tomato sauce
Bring a large pot of lightly salted water to a boil. Reduce heat to medium-low, cover potatoes, and cook until tender but still firm, about 20 minutes. Drain, and cool.
Meanwhile, in a medium saucepan, cook mushrooms and 2 cups cheese over medium heat until mushrooms are tender, about 5 minutes. Remove from heat, and set aside.
Place the mushrooms over a large rim of a large baking dish. Arrange mushrooms and cheese over spaghetti. Sprinkle evenly with mushrooms, and top with some cheese over pasta.
Cover spaghetti with mushroom mixture, and refrigerate overnight.
When the spaghetti is finished cooking, spoon sauce over spaghetti.