Preheat oven to 400°F. Prick sweet potatoes with a fork and place on a rimmed baking sheet lined with parchment paper. Bake 1 hour or until very tender. Remove from oven and let cool slightly. Reduce oven temperature to 350°F.
Meanwhile, to make the crust, stir together gingersnaps, coconut and butter in a medium bowl until moistened and well combined. Press mixture into and up the sides of a 9-inch pie dish. The crust will shrink so make the sides high. Bake about 15 minutes or until golden. Let cool slightly.
To finish making the filling, peel roasted potatoes and transfer flesh to the bowl of a food processor. Discard skins. Process until potatoes are pureed. Add coconut milk, brown sugar, eggs, cinnamon, nutmeg and salt and process until evenly combined.
Pour sweet potato filling into crust and bake about 50 minutes or until just set in center of pie. Let cool to room temperature on a wire rack. Serve or chill in refrigerator until ready to serve.