Begin by preheating your oven to 350°F (175°C) to ensure it’s ready for baking.
Bring a large pot of salted water to a boiling point. Once boiling, carefully add the cubed sweet potatoes. Allow them to cook for approximately 15-20 minutes, or until they are fork-tender. Once cooked, drain well and set them aside.
In a large mixing bowl, use a fork or potato masher to mash the sweet potatoes until they reach a smooth consistency, avoiding any lumps.
Incorporate the brown sugar, maple syrup, melted butter, vanilla extract, cinnamon, nutmeg, and salt into the mashed sweet potatoes. Stir vigorously until all ingredients are well combined and the mixture is creamy.
Grease a 9x13 inch baking dish with butter or cooking spray. Carefully pour the sweet potato mixture into the dish, spreading it out evenly across the base.
Evenly distribute the mini marshmallows over the sweet potato layer, ensuring complete coverage. If you opt for added texture, sprinkle chopped pecans or walnuts over the marshmallows.
Place the baking dish in the preheated oven and bake for 25-30 minutes. You’ll know it’s ready when the marshmallows are beautifully golden brown and toasted.
After baking, remove the casserole from the oven and let it cool for a few minutes before serving.
Notes
Serve warm, optionally with whipped cream or vanilla ice cream.