Preheat oven to 325 degrees F. In a large bowl, mix together the sweet pototoes, sugar, eggs, salt, butter, milk and vanilla. Mix until smooth. Transfer to 9x13 inch baking dish that's been sprayed with cooking spray.
In medium bowl, mix the sugar and flour. Cut in butter until the mixture is coarse. Stir in the pecans. Sprinkle the mixture over the sweet potato mixture.
Bake for 30 minutes or until the topping is lightly golden brown.