Jeanne's Thanksgiving Sweet Potatoes

3 c cold, mashed sweet potatoes, prepared without milk or butter
1/4 c butter, softened
1 t salt
1 c sugar
1/2 c milk
3 eggs
1 t vanilla

Topping

1/2 c packed brown sugar
1/4 c all purpose flour
1/2 chopped pecan
2 T cold butter

In a mixing bowl, mix sweet potatoes, butter, salt, sugar, milk, eggs and vanilla until smooth.  Transfer to a greased 2 quart baking dish.  In a small bowl, combine sugar, pecans and flour.  Cut in cold butter.  Sprinkle over potato mixture.  Bake, uncovered, at 325 degrees for 45-50 minutes or until golden brown.  Serves 8.