Lazy Perogy Casserole

15 lasagna noodles
2 cups cottage cheese
1 egg
1/4 teaspoon onion salt
1 cup shredded cheddar cheese
2 cups mashed potatoes
1/8 tsp pepper
1 cup butter or margarine
1 cup chopped onions

Cook noodles as directed on package.  Drain.  Line bottom of 9 x 13 inch pan.   In medium-sized bowl, mix cottage cheese, egg, onion salt, cheddar cheese, mashed potato and pepper together. Spoon over noodles and spread.  Cover with layer of noodles.  Melt butter in frying pan.  Saute onions slowly until clear and soft.  Pour over noodles.  Cover.  Bake 30 minutes in 350 F oven.  Let stand 10 minutes before cutting.  Serve with sour cream.