This is the recipe I use, I replaced all the fats with duck fat during my last prep of it, but I think it would have been improved slightly by using an herbed compound butter (or margarine, in my case, I chose duck fat and duck bacon for making this with the beef bourguingon for kosher reasons) for the butter they throw in before the potatoes go in the oven.
https://www.seriouseats.com/fondant-potatoes-recipe-5217320
This is the recipe I use, I replaced all the fats with duck fat during my last prep of it, but I think it would have been improved slightly by using an herbed compound butter (or margarine, in my case, I chose duck fat and duck bacon for making this with the beef bourguingon for kosher reasons) for the butter they throw in before the potatoes go in the oven.