@LifeInAHamsterWheel , here it is.
400 g macaroni (Recipe says elbow macaroni, but I usually use penne)
400 g really good strong Cheddar, grated
16 fl oz milk (I use semi-skimmed but you can use whole milk)
3 eggs
Salt, pepper, and a good dollop of English mustard, at least a heaped teaspoon.
Grease a large shallow-ish baking dish. Recipe says 2 quarts, but that’s American measures, I think their pint is 16 fl oz, so 4 times that.
Preheat oven to 180, 160 fan.
Cook the pasta in plenty of boiling salted water, drain well. While still hot, transfer to a large bowl, add the cheese and mix well.
Whisk the eggs with the milk, add S, P, and M, add it all to the pasta and cheese, mix thoroughly before transferring to baking dish.,
Before putting in the oven I cover the top with foil, to stop it browning too much.
Bake for about an hour, or until it’s looking reasonably well set - it doesn’t need to be set hard - it’ll firm up on cooling.
Allow to rest for 15 minutes before serving.
This cuts nicely into squares, and can also be served at room temp.
If you grate the cheese in advance, it’s very quick to put together.
It’s always very popular!