While I was making beef stroganoff with leftover roast beef, I started thinking about other ways to re-purpose leftovers. I've already heard of roast beef turning into shepherds pie, and leftover spaghetti being turned into a pasta cake.

What's your favourite hack for leftovers or one you've been meaning to try?

Are there any so good that you'll cook a dish just so you'll have leftovers to re-purpose.