
Arrange a rack in the middle of the oven and heat the oven to 400°F.
Cut 1 ½ pounds fingerling potatoes in half lengthwise. Place in a roasting pan or rimmed baking sheet. Drizzle with 3 tablespoons olive oil. Sprinkle with 1 teaspoon kosher salt, 1 teaspoon smoked paprika, ½ teaspoon garlic powder, ½ teaspoon onion powder, and ¼ teaspoon black pepper. Toss to combine. Arrange the potatoes in single layer cut-side down.
Roast until the bottoms are starting to turn golden-brown, about 30 minutes. Meanwhile, finely grate 2 ounces Parmesan cheese (about 1 lightly packed cup). Pick the leaves from 5 to 6 fresh parsley sprigs and finely chop until you have about 2 tablespoons.
Carefully flip over each potato with tongs or a thin metal spatula so they are now cut-side up. Sprinkle the Parmesan over the potatoes. (It’s OK if some fall onto the pan.) Roast until the potatoes are cooked through and the cheese is crisp and golden-brown, about 10 minutes more. Sprinkle with the parsley before serving.