For unattended (as in, we're in, but we're bound to forget to check it and let it boil dry, see every batch of Xmas puds we've EVER made that need 8 hours each) we use our rice cooker! This has the *design* feature that WHEN all the water is boiled away and the temperature tries to go above 100, PING, the thermostat switches to a "keep warm" mode which would be hard pushed to burn anything.