Personal Chef

If one is bringing a nonJewish personal chef to their house to cook food, can one allow them to use their own treif equipment food cooking foods or do they have to use your own kosher equipment?

My question stems from the fact that his equipment would be “eino Ben yomo” and my understanding is that food cooked with eino Ben yomo equipment is still kosher, but there is a prohibited to, lechatchila, do the cooking. Since this is a nonJew doing the cooking, does that prohibition still stand?

Lastly, would I be allowed to ask him to use his own equipment if that is easier for him, or am I only allowed to allow him to bring his own equipment if that is his own personal choice?

It would absolutely be prohibited to Lechatchila have your chef use his not kosher utensils.
Nevertheless depending on what they are they could be koshered