This recipe came from a Pepperidge Farm box, via my eldest sister (Gillian), more than 30 years ago!
Enough squash (crookneck/yellow/summer and zucchini) to cover bottom of casserole dish 3 deep when sliced thinly.
Salt and pepper it. Cover with grated carrot or parsnip.
Mix 1 can cream of mushroom soup with 8 oz sour cream. Spread out evenly over squash.
Cover with thin layer of seasoned bread crumbs or stuffing mix. Melt 1 stick butter or margarine and drizzle over top.
Bake 50-60 min at 350.