Casserole: the Good, the Bad and the Ugly...
Growing up my Mom refused to make us casseroles of any type. She believed (from childhood experience) that casseroles were just leftovers covered under a layer of shredded cheese. Until I moved out and went to college I thought the same thing.
However after my experiences having dinner at my friends houses and other extended family I've actually gotten to try all sorts of casseroles... The Good- Broc, cheese & rice. The Bad- anything made with Campbell's Tomato soup or topped with crushed saltines. And the Ugly- Tuna Noodle casserole. :)
I thought for years and years that I hated all casseroles. Mainly because anything my mother cooked and called "casserole" was just not nice at all. I remember prodding at that tasteless crud for hours. But like many different dishes and ingredients, I discovered I liked them after I left home and had the freedom to cook food that I wanted to eat. Now I love a good casserole, it makes me so happy in Winter to bung it in the oven, invite a bunch of people over to share and have that amazing smell drifting around. Favourites last Winter were a Tuscan beef stew, oxtail and osso bucco. When the weather starts cooling down I shall start looking for some new recipes to play with.
Mine are all hot - unless it counts when I am slumped in the open fridge door at 0200am, in a robe, spooning cold casserole into my mouth?
But in all serious I don't really know any "cold" casseroles. It is something I've only recently got into, after the horrors of my childhood. Oh, the only exception was my mothers beef in beer, but even then I only really liked the baguette slathered in mustard baked on top.
A casserole in UK/Australia is not the same as an American casserole. It was confusing for me when I moved to the US because in the UK a casserole is a meat and everything cooked in one pot like a stew generally done in the oven. Americans mean it as anything in a dish that's been in the oven so mac and cheese is a casserole.
Well, no, not "anything done in an oven." If you roast a chicken, that's a roast chicken, not a casserole. I don't know that the American definition is so distinctive from yours (though I don't see why they have to have meat). I don't think of mac-and-cheese as a casserole either: I think of it as mac-and-cheese. Though there are baked pasta dishes I'd consider casseroles.
I do adore one-pot dishes of all kinds, be they baked or stovetop. They're so versatile—the easiest thing to make up, along I suppose with stirfries.
We often do baked pasta--often in a 4 cheese sauce--that gets finished under the broiler. If this is a casserole, I'm all for it.
I grew up and live in Minnesota, land of the casserole called "hotdish". A hotdish, like a casserole can be anything and the results mostly depend on the quality of the cook and/or the recipe. My mother made a lot of casseroles and none of them were similar to what the OP described except for the ubiquitous tuna noodle casserole, but mom quit making that when I was quite young because nobody wanted to eat it (we got it at school lunch and I hated it). Most of the casseroles/hotdish were based on ground beef and could either go the tomato route or the bechamel route (mostly people used cream of something soup, but my mother thought they had too much fat and salt).
None of my mother's hotdishes were made with leftovers.
I am referring to my mother's casseroles because as an adult, we don't typically make them at home but sure we do get them at various church-type functions such as funerals.
I grew up on canned-soup casseroles. But as an adult I found that the casserole universe as much wider than I'd thought. Here are a couple that have been longtime favorites of mine.
James Beards Mushroom-Barley Casserole:
Brown Rice & Cheese Casserole- out of this world and really easy!