Peel and boil sweet potatoes. When tender, pour off water. Add butter, milk, sugar, egg and cinnamon and whip with mixer.
Pour mixture in a 9x9 square baking dish and smooth out. Combine flour, brown sugar, and cinnamon. Spread melted butter evenly over sweet potato mixture. Sprinkle topping over butter and bake for 20 - 25 minutes @ 375º to create a nice crust. Top with chopped pecans