Preheat oven to 350 degrees.
Grease a 13 x 9 casserole dish. Combine hot sweet potatoes, sugar, eggs, cream, half of the butter, cinnamon and nutmeg in a bowl; mix thoroughly. Add sweet potato mixture to greased casserole dish.
Combine Rice Krispies, pecans, walnuts and remaining butter and brown sugar into a bowl. Mix until crumbly. Sprinkle over sweet potato mixture.
Bake 40-45 minutes or until center is hot.