Option #1:  Roasting the Sweet Potatoes

1. Preheat your oven to 375 degrees F.
2. Clean the sweet potato skins.
3. Poke them with a fork.
4. Wrap the sweet potatoes in tin foil.
5. Bake for 1 1/2 hours, or until the sweet potatoes are soft.
6. Scrape the roasted sweet potato flesh from the skin.

Option #2: Boiling the Sweet Potatoes

1. Place the chopped and peeled sweet potatoes into a large saucepan, and cover with water by 1 inch.
2. Bring to a boil, then reduce to a simmer, and cook until the sweet potatoes are tender, about 15 to 20 minutes.

Making the sweet potato casserole filling:

1. Using a potato masher, mash the sweet potatoes until smooth (see tips above).
2. Place the cooked sweet potatoes into a skillet/pan. Heat the potatoes over medium heat, stirring, until any liquid has evaporated, about 2 minutes.
3. Remove the pan from the heat and add the milk, butter, nutmeg and salt and pepper.
4. Mix well.
5. Transfer the sweet potato mixture to a baking dish.

Baking the casserole.

1. Preheat your oven to 375 degrees F.
2. Cover the top of the sweet potatoes with a layer of marshmallows.
3. Bake until the casserole is warmed through and marshmallows are lightly browned, about 15 to 20 minutes.
4. Serve right away.