Wash the sweet potato and remove any bad spots, leaving the skin on. Line a baking sheet with parchment paper. Grate the sweet potato with the large side of a box grater onto the baking sheet. Spread the shreds into an even layer, then drizzle the top with the olive oil and sprinkle with the cornstarch, garlic powder, black pepper, and kosher salt. Mix it all together with your hands until evenly combined, then shape the potato into 6 loose mounds (see the photo).
Bake 30 minutes until lightly browned on the outsides and soft on the inside. Carefully remove the sweet potato hash browns from the baking sheet with a spatula.