1. Bake the sweet potatoes at 450F for 50 minutes to one hour, or until entirely soft.
2. Scrape out the middle of the sweet potatoes and discard the empty peels.
3. Mash the sweet potatoes with a spoon or masher.
4. Stir in melted butter, brown sugar, cinnamon, and eggs.
5. Pour the sweet potato mixture into a greased casserole dish.
6. Bake at 350F for 25 minutes.
Optional: After 20 minutes of baking, take out the casserole dish and spread marshmallows on top of the sweet potatoes in an even layer. Put the dish back in the oven and continue to bake 2-5 minutes, or until the marshmallows are golden and puffy. Watch the oven closely, marshmallows burn quickly!!