Preheat your oven to 425 degrees Fahrenheit. While the oven is heating, wash your green beans thoroughly and trim off the tough stem ends. Pat the beans completely dry with a clean kitchen towel or paper towels, as any excess moisture will steam the beans rather than roasting them to a crisp.
Place the dried green beans into a large mixing bowl. Drizzle with the olive oil and toss them well to ensure every bean is lightly coated. In a small separate bowl, whisk together the garlic powder, onion powder, salt, and black pepper, then sprinkle this mixture over the beans and toss again.
Add the grated parmesan cheese and panko breadcrumbs to the bowl. Use your hands or a pair of tongs to coat the beans evenly. The oil will help the cheese and crumbs adhere to the surface of the vegetables, creating that signature crust once they hit the heat.
Spread the beans out in a single layer on a large rimmed baking sheet. Avoid overcrowding the pan, as this allows the air to circulate for maximum crispiness. Roast for 18 to 22 minutes, or until the beans are tender and the breadcrumbs are golden brown. Toss them halfway through the cooking time for even browning.
Remove the pan from the oven and immediately sprinkle with fresh parsley. Transfer the beans to a warm serving platter and serve while they are hot and the coating is still crunchy.
