This has got to be one of the simplest things to make, anywhere. Pop all the ingredients into a pre-heated slow cooker.
Cook for 8 hours on low, or 4 hours on high. Give it a little stir after an hour or so, to mix the sugar and butter. Keep an eye on it, and add a little more milk if needed.
Serve with a sprinkling of nutmeg, cinnamon or chocolate powder.