Preheat the oven to 425-degrees Fahrenheit
Rinse and pat dry the potatoes.
Line a baking sheet with foil and place the potatoes on the foil to bake.
Bake until tender for about 1 hour. You want them to be extra soft.
Cut them open and scoop out the sweet potato and place in a bowl, leaving the skin behind.
Mash the sweet potatoes with butter, sugar, salt, vanilla, and heavy cream while they’re hot.
Mash until the texture is smooth or how you like it. You can also use an electric mixer or blender to get smooth potatoes.
Spread the mashed sweet potatoes into a casserole dish.
Top with regular or large marshmallows, OR spread the homemade marshmallow fluff over the mashed sweet potatoes.
If you're using marshmallows, bake the dish in a 350-degree oven for 5 mins or until the marshmallows are golden brown.
Using a kitchen torch, torch the marshmallow fluff until it’s toasty!