I actually use GPT-3.5 (the free one) for my meal planning, GPT-4 seemed like it was smarter than it needed to be and it works pretty well - Claude should also work. The trick with LLMs, as always, is to avoid treating them like people and treat them more like a tool that will do exactly what you ask of them. So for instance, instead of “What should I eat for dinner?” (which implies personality, desires, and preferences and can throw it off), you should ask “List meals I can make using (ingredients) and other common ingredients” and then “Write a recipe for (option)” which are both mostly objective questions. You can ask for a particular style, culture, etc too. Also keep in mind its limits, it knows cooking from ingesting millions of cooking blog posts, so it won’t necessarily know exact proportions or unusual recipes/ingredients/combinations.