Preheat oven to 375°F (190°C) and grease a 9x13-inch baking dish.
Prepare the sweet potato mixture: In a large bowl, mix together mashed sweet potatoes, brown sugar, half and half, softened butter, egg, vanilla extract, and salt until smooth.
Spread the sweet potato mixture evenly into the prepared baking dish.
Make the pecan topping: In a small bowl, combine brown sugar, flour, pecans, and melted butter. Stir until a crumbly texture forms.
Add the topping evenly over the sweet potato layer.
Bake for 35 minutes, or until the topping is golden and crispy.
Cool for 20 minutes before serving. Enjoy!