Sweet Potato Streusel

2 sweet potatoes 1/8 teaspoon salt 2 tablespoon butter 1 egg 1/4 teaspoon vanilla extract 1/8 teaspoon ground cinnamon 2 tablespoons white sugar 1 1/2 teaspoons heavy cream 1 tablespoon butter, softened 2 1/4 teaspoons all-purpose flour 3 tablespoons packed brown sugar 2 tablespoons chopped pecans


 * Preheat oven to 350 F (176 C/gas mark 4). Grease a baking dish.


 * Heat water in a saucepan. Peel sweet potatoes, chop and place in boiling water. Boil for 15 minutes and drain. Return sweet potatoes to pan and add salt, butter, egg, vanilla extract, cinnamon, sugar, and heavy cream. Transfer to the prepared baking dish.


 * In a medium bowl, combine butter, flour, brown sugar, and chopped pecans. Mix with a fork to the consistency of course meal. Sprinkle over the sweet potato mixture.


 * Bake for 30 minutes, until the topping is crisp and slightly brown.