Can a Jew who understands the laws of Kashrut but is not personally observant cook for a Kosher-observant Jew? For example, can a Jewish but non-observant parent cook for his Orthodox child?
Both of you are Jewish. If you are concerned about the concept of 'Bishul Akum' - a Gentile turning on the stove, it obviously doesn't apply, here.
I understand that perhaps, you have a separate concern that your mom may bring in non-kosher food, may mix meat with dairy pots or cook food that is kosher but not to your kashrut standards. If these are concerns, you can explain your rules and needs to her, and hopefully, she will cooperate. In short, if she is using your own food and cookware and utensils, her level of observance is irrelevant.