Part of the problem with the flat buttons you touch is that you can't really tell where they are. A dial was much easier for her to understand than trying to manage to remember where a dozen buttons are and what order they're in.

We got the microwave with the dial after she accidentally microwaved something until it caused a fire in there which flooded the room with smoke and was so bad I had to simply throw it out.

If I wanted to use my stove, microwave or dishwasher (all flat buttons), I might try to put a little Sugru on the surface to outline the important ones like the +30 seconds button.

They have tactile stickers specifically for this kind of thing, I think they even have different textures a blind person can distinguish

We did that, but the old one didn't have a +30 second button and just had little sticky pads on every button, since you had to use numbers, which didn't make it clear what was what. And some things have 9 at the top, others put it at the bottom, so it's not that hard to forget.

Either way, a physical dial was much easier to use than trying to remember the layout of the number pad, which button is power/cancel/etc.