More detail/background: she moved back to Canada and in with us November 2024. Our basement was renovated to her specifications, so she has her own safe space near us but separate for her independence. She has access to us anytime she might need help, etc. Most meals are with us upstairs.
Even so, she has a decent sized fridge/freezer, sink and air fryer down there for cooking - and she makes some weird concoctions, but that's besides the point. Food safety is questionable... Often we have to toss expired food/milk/sour cream/etc because she just keeps stuff and ignores mould and off odours.
She has left cooked food out overnight - on our stove upstairs (we disposed of it). Forgotten things in the oven upstairs, too. With the oven on, because she "thought it would turn off when the food was ready". We had to explain an oven is not the same as a microwave.
We are limited due to lack of venting down there and concerned about open vs enclosed cooking spaces, hence no stovetop. But not sure how to stop her from buying a hot plate. She's decided on an inversion one and has one of her friends telling her it's a "wonderful" idea.