01 -  Preheat oven to 350°F (175°C). Grease a 2-quart baking dish thoroughly to prevent sticking. 
 02 -  In a large bowl, combine mashed sweet potatoes, melted butter, brown sugar, heavy cream, eggs, vanilla extract, cinnamon, nutmeg, and salt. Mix until the texture is smooth and homogenous. 
 03 -  Transfer the sweet potato mixture evenly into the prepared baking dish, smoothing the surface with a spatula. 
 04 -  In a small bowl, blend chopped pecans, flour, brown sugar, and melted butter until a coarse crumb forms. 
 05 -  Distribute the pecan topping evenly over the sweet potato base. Bake for 35 minutes or until the topping is golden brown and the filling is set. 
 06 -  While the casserole bakes, place granulated sugar and water in a small saucepan over medium heat. Stir gently until dissolved, then cook undisturbed until an amber caramel forms. Remove from heat and immediately whisk in heavy cream, butter, cinnamon, and salt until smooth. Let the sauce cool slightly. 
 07 -  Portion the warm casserole into individual bowls. Drizzle generously with spiced caramel sauce before topping each portion with a scoop of vanilla ice cream. Serve immediately.