Preheat oven to 350°F. Pour 2 cups of water into a medium size cooking pan. While waiting for the water to boil, peel the medium sweet potato, wash off, and then slice down the middle. Put them in the boiled water, turn down to medium heat. Cook in boiled water for about 25-30 minutes depending on the sweet potato. Check with a fork to see if potato is done.
When done, take out into a medium size mixing bowl, mash down sweet potato with a masher utensil, let cool for about 5-7 minutes, and then add eggs and butter, mix together. Then add the sugar and mix well. Add the vanilla flavor, mix well. Then add the evaporated milk, mix well. Then lastly, sprinkle nutmeg to desired taste, mix well.
Pour in a deep dish pie crust, and bake for 25-30 minutes. Stick a toothpick in to see if ready to take out. When done, let stand for 5-10 minutes to cool. Then add pecans completely over the top of the pie. Then add your marshmallows for a treat that's out of this world. Indulge and enjoy.....