Heat oven to 325.

Cook sweet potatoes in a med saucepan with water to cover. Cook over med high heat until tender. Drain and mash.

In a large bowl mix potatoes, white sugar, eggs, salt, butter, milk and vanilla extract. Mix until smooth. Transfer to a 9x13 baking dish.

In a medium bowl mix the brown sugar and flour. Cut in the butter until the mix is coarse. Stir in the pecans. Sprinkle over the top of the potato mix.

Bake for 30 minutes or until topping is lightly browned.