Place the Brussels sprouts into a large mixing bowl, then pour over the melted butter and olive oil. Stir thoroughly to ensure each sprout is evenly coated in the fats, which will help the seasonings adhere.

Incorporate the salt, pepper, garlic powder, onion powder, panko breadcrumbs, and grated Parmesan cheese into the bowl. Toss everything together until the Brussels sprouts are uniformly encrusted with the seasoned crumb mixture.

Spread the coated sprouts cut-side down in a single layer on a prepared baking sheet, ensuring adequate space between each for optimal crispiness. Press any bare sides gently into the leftover breadcrumb mixture to fully coat them.

Sprinkle any excess Parmesan-panko mixture over the tops of the sprouts and press down lightly to adhere.

Roast in a 400°F oven for 20 minutes. Turn the sprouts over and continue baking for an additional 5–10 minutes, or until deeply golden and crisp.

Allow the sprouts to cool for five minutes after baking. Transfer them to a serving dish and, if desired, dust with more Parmesan cheese before serving warm.