Pennsylvania New Year's Day Potatoes.

My mother in law used to make potatoes on New Year’s Day and I’m trying to figure out how she did it. (Not able to ask her). I know they were baked in foil, but they were so creamy inside. They weren’t just regular baked potatoes in foil. (I tried, didn’t work). So I’m wondering if anyone knows the trick, or what she did to make these. They were so very good.