Warm and mash sweet potatoes. Melt 1/2 stick of butter.
Mix sweet potatoes, sugar, melted butter, milk, vanilla and cinnamon.
Bake at 350 degrees for 45 minutes.
While sweet potatoes are cooking, Crush corn flakes and melt the remaining 1/2 stick of butter.
Mix the crushed cornflakes, melted butter and brown sugar together.
Remove sweet potatoes from the oven. Carefully spread the cereal mixture over the sweet potatoes. Return to oven and cook an additional 15 minutes or until topping is crisp. Let stand 5 minutes before serving.