Preheat oven to 400°F. Line a large baking pan with parchment paper or grease with non-stick cooking spray.
Spread green beans in an even layer on prepared pan. Drizzle with olive oil and then season with garlic powder, salt, and pepper. Toss to coat. Drizzle lemon juice over beans.
Roast for 12-15 minutes, or until green beans are tender, but still slightly crisp.
Garnish with a touch of Parmesan cheese, if desired. Serve immediately.