Preheat oven to 375°F. Roll out pie dough and fit into a 9-inch pie plate. Crimp edges, prick bottom with a fork, line with parchment, fill with pie weights, and blind bake for 10 minutes. Remove weights and parchment, set aside.
If not already roasted, pierce sweet potatoes with a fork and roast at 400°F for 45-55 minutes until tender. Cool, peel, and mash until smooth. Measure 1 1/2 cups mashed sweet potato.
In a bowl, combine mashed sweet potato, granulated sugar, and 1/4 cup melted butter. Add 1 egg, heavy cream, 1 teaspoon vanilla, cinnamon, nutmeg, and 1/4 teaspoon salt. Beat with a hand mixer until smooth, about 1-2 minutes.
Pour sweet potato filling into the pre-baked crust and spread evenly. Bake at 375°F for 20 minutes until edges are set but center still jiggles slightly. Remove pie from oven and reduce temperature to 350°F.
In a separate bowl, whisk together the remaining 2 eggs, corn syrup, brown sugar, 3 tablespoons melted butter, remaining 1 teaspoon vanilla, remaining 1/4 teaspoon salt, and bourbon if using. Stir in pecan halves until fully coated.
Carefully pour the pecan mixture over the partially baked sweet potato layer. Use a spoon to spread pecans into an even single layer.
Cover crust edges with a pie crust shield or foil to prevent over-browning. Bake at 350°F for 35-40 minutes until pecan layer is set and no longer jiggles in the center. Tent with foil if top browns too quickly.
Transfer pie to a cooling rack and cool at room temperature for at least 2 hours. For cleanest slices, refrigerate for another 2 hours or overnight before cutting with a sharp knife, wiping blade clean between cuts.