I am originally from the midwest (MN!), and also love a good casserole. I have found that many of the traditional casserole recipes are too heavy for my tastes now, and also generally full of meat, so it has been fun adapting and updating the casserole for how I eat now.
It’s too hot in the summer to use our oven, so I haven’t baked on in a long time. Off the top of my head, one of the house favorites is (store bought) gnocchi (cooked first), spinach, canned tomatoes, garlic, and lots of mozzarella cheese for 30 mins at 350.