Cook noodles according to package directions. Drain. Add margarine, celery salt and pepper. Toss lightly. In large bowl combine noodles, spinach, meat, mushrooms, cottage cheese, pimiento and Cheddar cheese. Spoon into 3 qt. casserole. Bake for 30-35 mins. at 350 F. Stir 2-3 times while cooking so spinach doesn't dry out.=20