Melt 1 stick butter; stir in 1/2 package Pepperidge Corn Bread stuffing. Line bottom of 2-quart baking dish with 1/2 of mixture. Combine 2 cups cooked squash with 1 can cream of chicken soup, 1 small carton sour cream and 2 finely chopped onions. Put in casserole. Put remaining stuffing on top. Bake 1 hour 15 minutes at 350 degrees. Can be frozen. If not frozen, bake 1 hour.