TL;DW: put an IR camera inside to see the temperature of the food, and then a screen on the front of the microwave to show the temperature what's inside. You can then see when it turns all white, it's hot (on the outside at least). - Amit Patel

And then also use the screen for other purposes. - Anne Bouey

Advertisements of course! - Amit Patel

Haha! Of course. - Anne Bouey