1. Cook sweet potatoes until soft, remove skins. Cut into 1/2 inch slices. Set aside.
2. In a pan, melt butter, brown sugar, cream and salt on medium heat until melted and bubbly.
3. Add sweet potato slices to the brown sugar mixture and mix to cover in the sauce. Cook until sweet potatoes are heated through.
4. Transfer to an oven safe serving dish and top with marshmallows (mini or large are fine). Put under the broiler until golden brown. Watch very carefully because they can burn quickly.