Preheat your oven to 375 degrees Fahrenheit.
Spray a medium-size casserole dish with nonstick spray.
In a large mixing bowl, beat together 3/4 cup sugar, 1/4 tsp salt, 1/4 tsp vanilla extract, 2 cups mashed sweet potatoes, 1 well-beaten egg, and 1/4 cup melted butter.
Mix until smooth and well-combined.
Pour the sweet potato mixture into the greased casserole dish.
Spread it out evenly.
Prepare the crust by combining 1/2 cup brown sugar, 1/4 cup flour, 1/2 cup chopped pecans, and 1/4 cup melted butter in a separate mixing bowl.
Stir well until the mixture becomes crumbly.
Sprinkle the crust mixture evenly on top of the sweet potato mixture.
Bake in preheated oven for 30 minutes or until the top is golden and slightly crispy.