I cubed 6 summer squash (a mix of zucchini and crookneck) and a VERY large tomato, tossed them on a sheet pan (1" sides) with olive oil and a hefty amount of sea salt, and put them into a 400* oven to roast. I mixed them up, flipping them over as best I could, after 15 minutes.
During that 15 minutes I browned some crumbled ground beef - about 1.5# - and a chopped, large onion with salt and dried basil in oil. When it was done I drained it, then added container (16 oz I think?) of full-fat sour cream, mixing it in thoroughly, and turned the heat to the lowest setting. Covered, it waited quite patiently for the vegetables to finish.
After greasing my 11x14 Anchor baking dish with oil, I poured the roasted vegetables into it. While they were still hot I sprinkled about a cup of mixed shredded cheese over them. Then I spread the meat/sauce mixture over the cheese, then I put another half-cup or so of the cheeses on top, and sprinkled it with parmesan (from the can).
Since it was the night before the potluck, I covered it and put it in the fridge.
The next morning I popped it - uncovered - into the oven at the church at 300*. It came out well-browned, crispy around the edges and on top, and beautiful an hour later. Probably it would have been just as good heated half that time,
I was really delighted with how it tasted, and can't wait to make it again, it was SO delicious!