1. Preheat your oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish with butter.
2. Place the peeled and chopped sweet potatoes in a large pot and cover with water. Bring to a boil and cook until tender, about 20 minutes. Drain and let cool slightly.
3. Transfer the sweet potatoes to a large mixing bowl and mash them until smooth. I like to leave a few lumps here and there—it reminds me of Mama Lou’s hands mashing by feel, not perfection.
4. Add the granulated sugar, melted butter, milk, eggs, vanilla extract, cinnamon, nutmeg, and salt to the mashed sweet potatoes. Mix well until everything is fully combined and creamy.
5. Pour the sweet potato mixture into the prepared baking dish, spreading it evenly.
6. In a separate bowl, combine chopped pecans, brown sugar, and 2 tablespoons of melted butter. Sprinkle this topping evenly over the sweet potato layer. If you’re adding marshmallows, sprinkle them on top of the pecan mixture for the last 10 minutes of baking.
7. Bake uncovered for 30-35 minutes until the topping is golden brown and the casserole is set in the center. If using marshmallows, add them after 25 minutes of baking and continue for the remaining 10 minutes.
8. Remove from the oven and let it cool for 10 minutes before serving. This cooling step helps the casserole hold its shape and deepens the flavors.

One of my favorite memories with Ouma was sneaking bites of the pecan topping while it was still warm—always a reminder that the best cooking moments happen when no one’s watching!