Creating Sweet Potato Casserole is simple and enjoyable if you follow these straightforward steps:

1. Preheat the Oven: Begin by preheating your oven to 350°F (175°C).
2. Cook the Sweet Potatoes: Peel the sweet potatoes and cut them into chunks. Boil them in a pot of water until tender, about 15-20 minutes. Drain and let cool slightly.
3. Mash the Potatoes: In a large mixing bowl, mash the sweet potatoes using a potato masher until smooth.
4. Combine Ingredients: Mix in the granulated sugar, melted butter, milk, eggs, vanilla extract, cinnamon, nutmeg, and salt until well combined and fluffy.
5. Transfer to Casserole Dish: Pour the sweet potato mixture into a greased 9×13-inch casserole dish, spreading it evenly.
6. Add Topping: If using marshmallows, sprinkle them evenly across the top. If using pecans, sprinkle them on top instead.
7. Bake: Place in the preheated oven and bake for 35-40 minutes, or until the topping is golden brown and the casserole is heated through.
8. Cool: Remove from the oven and let it cool for about 10-15 minutes before serving.

These straightforward steps will guide you in crafting this incredible Sweet Potato Casserole effortlessly, making it a beloved addition to your meal repertoire.