Looking for a simple one touch microwave with 5 minute setting. Any ideas?

Hi, I am trying to find a microwave for my mum. She has dementia but is able to follow simple processes with the microwave. She only reheats frozen meals and we would like her to be able to push one button then the start button. Does anyone know of a microwave that has either a preset function at 5 minutes (perhaps for ready meals or potato) or a 5 minute button. We don't think a dial would work for her. Any ideas? Thank you.