Cook sweet potatoes in desired manner, until soft. See notes.
Preheat oven to 375 degrees F. Spray a 2 qt baking dish with nonstick spray (I use coconut oil spray). Set aside.
In a large bowl, combine cooked sweet potatoes, granulated sugar, salt, vanilla, eggs and melted butter. Beat with an electric mixer for about 4-5 minutes, until fluffy and smooth.
Pour into prepared dish. Bake for 25 minutes.
While baking, prepare streusel topping by combining brown sugar, flour, pecans, and melted butter in a small bowl. Mix with a fork and set aside.
Sprinkle the baked sweet potato mixture with streusel and return to oven for about 10-15 minutes until crumble is lightly browned. Serve immediately or cover with foil and serve in 30 minutes.
For the sweet potatoes you can cook them your favorite way. Bake in a 400 degree F oven for one hour. Or pierce with fork and microwave for 15 minutes (or more depending on size). Or peel and boil them for 30 minutes.