Preheat your oven to 400°F (200°C). Position a rack in the middle.

Pour the melted butter into a 9x13 baking pan and spread so the bottom is coated.

Wash and dry the small potatoes. Cut each in half. Score an “X” on the cut surface of each half with a sharp knife.

In a small bowl, combine the Parmesan, garlic powder, onion powder, parsley, salt, and black pepper. Stir until evenly mixed. Reserve about 1 tablespoon of the mixture for finishing.

Sprinkle most of the cheese-and-spice mix over the melted butter in the pan to form a flavorful bed.

Place each potato half cut-side down onto the seasoned butter and cheese, snug but not overlapping.

Drizzle the potato tops with olive oil, then dust them with the reserved tablespoon of seasoning.

Roast uncovered for 40 minutes, or until the potatoes are fork-tender and the edges are golden and crisp. If you want additional color, run them under the broiler for 1–2 minutes while watching closely.

Let rest for a few minutes, then serve warm.