Step 1: Preheat your oven to 400°F (200°C). Prick the sweet potatoes with a fork and roast for 45-60 minutes until very soft. Let them cool, peel off the skins, and mash the flesh until smooth.
Step 2: Reduce oven temperature to 350°F (175°C). In a food processor, pulse pecans, flour, and brown sugar. Add the cold cubed butter and pulse until the mixture resembles coarse crumbs.
Step 3: Press the pecan mixture firmly into the bottom and up the sides of a 9-inch pie dish. Bake the crust for 8-10 minutes until slightly toasted, then remove and set aside.
Step 4: In a large mixing bowl, beat the mashed sweet potatoes with the 1/2 cup softened butter until well combined.
Step 5: Add the granulated sugar, heavy cream, eggs, vanilla, cinnamon, nutmeg, and salt. Mix on medium speed until the filling is silky and uniform.
Step 6: Pour the sweet potato filling into the pre-baked pecan crust, smoothing the top with a spatula.
Step 7: Bake the pie for 45-50 minutes, or until the edges are set and the center has a slight jiggle.
Step 8: Remove from the oven and allow the pie to cool completely on a wire rack for at least 2 hours before slicing to ensure it sets properly.