Boil the Sweet Potatoes: Place the peeled and cut sweet potatoes in a large pot of water. Bring to a boil and cook until they are tender, about 15-20 minutes.
Mash the Sweet Potatoes: Drain the sweet potatoes and transfer them to a large mixing bowl. Use a potato masher or an electric mixer to mash them until smooth.
Combine the Ingredients: Add the light brown sugar, melted butter, vanilla extract, cinnamon, salt, and nutmeg to the mashed sweet potatoes. Mix thoroughly until all ingredients are well incorporated.
Preheat the Oven: Preheat your oven to 350°F (175°C).
Transfer to Baking Dish: Spread the sweet potato mixture evenly in a greased baking dish.
Bake: Place the dish in the oven and bake for 30-35 minutes, or until the top is slightly caramelized and the casserole is heated through.