Sarasewing is the recipe I use, except, I like my sweet potatoes baked in the oven.
Line a pan with foil and rub oil on the foil....I know how it sounds....rub oil on the sweet potatoes and lay on the oiled foil with space between them. Bake at 350 to 400 about an hour, they are done when you press them lightly on the side and they are soft; or poke a fork in them and if soft they are ready.
You can split them while hot, add butter and cinnamon and eat as a side dish, I like mine with plain butter.
Making the souffle, let them cool a bit, peel them, mash them and make your souffle/casserole.
I have to make this every Thanksgiving, Christmas, Easter or any other time we all gather.
Hope you enjoy,
delma