Preheat the oven to 425 degrees. Spray a baking sheet with cooking spray (cover with foil for easier clean up). Combine the panko breadcrumbs, Parmesan cheese, lemon pepper, garlic powder, salt, and pepper on a shallow plate.
Press one side of the chicken into the egg and then into the panko and Parmesan mixture. Place it on the baking sheet with the breading up. To make it extra crispy, spray the chicken with cooking spray or drizzle with a little olive oil.
Toss the green beans with olive oil and season with salt and pepper. Spread out on the baking sheet around the chicken. If you prefer your green beans more tender-crisp, add them in the last 8 minutes of cooking.