Preheat oven to 350 degrees F (175 degrees C). Grease one 2 quart casserole dish.
In a large bowl, blend together the sweet potatoes, milk, orange juice, eggs, vanilla, sugar, salt, butter, nutmeg and cinnamon. Pour into prepared casserole dish.
Mix together the 1/4 cup butter, brown sugar, flour and pecans; sprinkle over sweet potato mixture.
Bake at 350 degrees F (175 degrees C) for 45 minutes.