We’ve all heard the expression “like a hot knife through butter.” But actually having a hot knife on hand was never really convenient… until now. The Warburtons Toastie Knife heats to 41.8 degrees Celsius, which is supposedly the optimum temperature to spread butter. The knife is powered by two AA batteries in the handle, and is turned on with the push of a button. A flashing LED indicates that the heating element has been activated, and 30 seconds later you’re good to go.