I ate this first in a resturant my nephew worked at,20 or so years ago. It was so good I had to try it at home ! We've been having this ever since when the gardens are harvested and any time I can get the squash!Omitt the pepperoni and you have a veggie dish.My whole family eats this and my ladies card club loves it too. Give it a try you'll be glad you did. I will post a picture when I make it next.
In a 9x13 baking dish put small amount of spaghetti sauce on bottom ,next layer 1/2 the onion,zuchinni,yellow squash ,pepperoni and 1/2 mozzarella cheese sprinkle with half of the Parmesan repeat layers Pour remaining spaghetti sauce over top cover with foil bake 350 for about 25-30 min.
Any additions are fine ,mushrooms ,peppers etc. what ever you may like i like it as is. I use this as a side or main course. with hard rolls and side salad if we want. Enjoy