My mom's Sweet Potatoes

A Thanksgiving tradition.
It's not a very specific recipe. I just took a few yams and cooked them the day before and put them in the fridge.
Then the day I made them, I peeled them, sliced them, and put them in my 9x13 pan. Sprinkle brown sugar over all of them and then put some slices of butter and some pecans on top of that. Cook at 350 for about 30 minutes, then put marshmallows on top and put back in oven until slightly browned.
Yum!