Our routine is:
I cook the roast (almost always chicken)
We eat the roast
Mrs F strip the meat off the carcass, while it’s still warm.
Then she gets a pyrex dish, layer of chicken, sprinkling of the leftover veg, leftover gravy, layer of mash, top with grated cheese, leave to cool then in the fridge overnight. Next day bake and serve with the lefotver yorkshires, warmed separately to retain texture.