Summer Squash and Carrot Casserole without butter

2 lbs summer squash or 2 lbs zucchini , sliced (6 cups) 1/4 cup onion , chopped 1 (10 ounce) can cream of chicken soup 1 cup sour cream 1 cup carrot ,[...]

2 small zucchini , ends trimmed 2 summer squash, ends trimmed 2 large carrots , peeled and ends trimmed (1/2 lb) 24 large basil leaves , cut in julienne 3[...]