This was fabulous! We ate it as a main dish, and it was more than two of us could finish. I didn't use olives, but I mixed in some dried onion flakes with the squash. I didn't have tomatoes so I topped with mushrooms - will definitely make it again to try the tomatoes. Also, I used more garlic than called for (I had garlic powder instead of garlic salt and messed up the conversion) but I liked it better that way.
Delicious and unusual vegetable casserole! I served it with grilled pork chops, tossed salad, and sour dough bread. Thanks so much.