I sometimes just make a cheese and onion crustless pie. I haven't got a recipe - I just get about 5 eggs, separate and beat a couple of the whites, then beat them all together and pour them into a buttered pie dish. I grate some cheese into it, and drop in some finely chopped onion. Bake at 200c for about 45 minutes -ish.
It's a nice snack, or can be used as the protein in a main meal. It keeps itself together so that you can cut it into wedges, even without pastry.
I don't remember cheese and onion pie in school dinners at all - it was always meat or fish, unfortunately.
I do remember a failed potato crop one year, ans schools were ordered to provide bread and butter instead. They probably meant margerine, but orders are orders, and we got lovely freshly backed bread and loads of butter.
PS
Margerine or its various modern equivalents is something I refuse to eat - hate the taste. It's butter or nothing.