Preheat the oven to 350 degrees F.
Place the sweet potatoes in a pot and pour water until potatoes are covered. Bring to a boil. Reduce heat to medium, and simmer until very tender.
Peel the potatoes and transfer to a large mixing bowl. Mash with a potato masher. Let cool about 5-10 minutes.
Add in the powdered sugar, milk, beaten eggs, vanilla extract and 3 tablespoons melted butter. Combine well.
Brush a 6 x 9 inch baking dish with melted butter. Place the potato mixture in the baking dish and spread evenly.
To prepare the topping, in a separate bowl, combine the sugar, nutmeg, cinnamon, chopped pecans, flour, and ½ cup melted butter.
Spread the topping evenly over the sweet potatoes.
Bake in the oven for 30-35 minutes or until the pecan topping is golden. Serve it warm or cold.
