Who knew zucchini was so beautiful inside?
Anyway ...
I know. It looks like lasagna. It's not. It's a zucchini, onion and swiss chard casserole. Heavenly! 
The swiss chard doesn't have to be in there, but it's good, so why not? I guess you could also do spinach? Either one will need to be blanched in boiling water, then chopped fine. 
The absolute key to getting the right texture is to use a mandolin to slice the squash and onions paper thin. Texture matters. 
So, take your favorite red sauce. I like a red sauce made with sauteed onions in butter, crushed tomatoes, a bit of cream, a dash of sugar and a few tablespoons of apple cider vinegar (yes, you heard that right. Try it. It's amazing). You can use anything you like, even jar sauce (Yeah, I said it. So what. I don't use it, but you can).
A little sauce on the bottom, then spread half of the squash, chard and onions -- add a light bit of cheese to hold it together, I like mozzerella but you can also use cheddar -- then spread the rest of the squash/chard/onions and top with more sauce. A little cheese on top also. Just a little though. It's about the vegetables, not the cheese. Then into a 350 oven for about 30 minutes.
This is how it looks at the end -- before the final topping of sauce. This is delicious! 
