Preheat the oven to 425°F. Set aside a baking sheet lightly coated with nonstick spray.
Coat the green beans in the olive oil, then add the parmesan cheese, garlic powder, salt and pepper and mix to coat.
Bake for 15 minutes in an equal layer on a baking sheet. Flip the green beans with a spatula and simmer for another 10 minutes, or until tender. Keep warm.