1. Preheat your oven to 350°F (175°C). Lightly grease a 9×13 inch baking dish with butter or nonstick spray.
2. Place the peeled and cubed sweet potatoes in a large pot and cover with cold water. Bring to a boil and cook until tender, about 15-20 minutes. Drain well.
3. Using a potato masher or hand mixer, mash the sweet potatoes until smooth but still a bit textured for that homemade feel.
4. Stir in the melted butter, brown sugar, milk (or cream), vanilla extract, cinnamon, nutmeg, and salt. Mix thoroughly until everything is combined and creamy.
5. Transfer the sweet potato mixture to your prepared baking dish, spreading it out evenly.
6. Sprinkle the mini marshmallows evenly over the top of the sweet potatoes. If you’re using nuts, sprinkle them on top of the marshmallows for added texture and flavor.
7. Bake uncovered for 25-30 minutes, or until the marshmallows are golden brown and toasted. Keep a close eye in the last 5 minutes to prevent burning—there’s a fine line between perfect and charred!
8. Remove from the oven and let it sit for 5 minutes before serving. This helps the casserole settle and makes it easier to scoop.

One tip I learned from Mama Lou is to avoid over-whipping the sweet potatoes; you want a bit of rustic texture to remind you that this is a lovingly made dish, not a restaurant puree. And if you’re like my sister Ouma, you might sneak a toasted marshmallow or two straight from the oven—it’s impossible to resist!