Suggest They Entertain You Instead
There are some guests who feel compelled to offer to help and then ask a question like, "What are these nuts?" in reference to the garlic cloves on the counter (true story). This is when you say, "Why don't you pour yourself a drink and tell me the latest gossip while I cook?" That way, you're not being abandoned in the kitchen, but you're also not putting yourself in the awkward and stressful situation of having to coach a culinary newbie through every single step (and eat dinner sometime around midnight).