In a large bowl, combine the sweet potatoes, sugar, salt, and vanilla.
Whip with electric beaters or in a stand mixer, and add the eggs and melted butter. Beat until light and fluffy.
Pour the sweet potato mixture into a casserole dish coated with cooking spray. Or you can make single servings. At this point, you can cover it and keep it in the fridge for a day or two. You can also make the topping ahead of time and keep it in a container until you bake off the sweet potatoes. Bake in a 375 degree oven for 25 minutes.
Meanwhile, start the topping. In a small bowl, combine the brown sugar, flour, and pecans.
Pour in the melted butter.
Stir until combined.
Add the topping to the sweet potatoes, and add back to the oven for another 10 minutes. Let stand for 30 minutes before serving.