wash and cut potatoes in half lengthwise. Drizzle with salt, pepper and olive oil. Place the sweet potatoes in a single layer on a rimmed baking sheet.
bake in oven until fork tender, about 40 minutes. Once softened, remove from oven and cool 10 minutes.
In a large sauté pan, combine the brown sugar and butter, heat on medium low heat and stir until butter dissolves and mixture combines. Stir occasionally to prevent sugar from lumping.
Remove from heat and set aside. Use a large spoon to remove the pulp from the potato quarters and discard the skins.
Place the potatoes in a large mixing bowl. While using a hand masher to mash the potatoes slowly add the cream and melted butter to the potatoes.Mash until fully combined. Using an electric mixer fitted with a whisk attachment, whip the potatoes until almost smooth.
Add the brown sugar mixture, salt and pepper and whisk on medium speed until fully combined. Add the pecans and raisins, if using. Whisk additional time to combine mixture.
Place smooth potato mixture into a 9x13 glass baking dish. Top the mixture with small marshmallows. Brush the marshmallows with melted butter. Bake in oven until mixture is heated through and the marshmallows are lightly browned.
Remove from oven and let stand to cool for 10 minutes. Serve hot.