Preheat your oven to 400°F (200°C). On a large rimmed baking sheet, toss the trimmed green beans with 1 tablespoon of olive oil, a pinch of salt, and pepper. Spread them in an even layer, leaving space in the center for the chicken. Nestle the lemon wedges among the green beans.
Pat the chicken breasts completely dry with paper towels. If they are uneven, pound the thicker parts to a uniform 1/2 to 3/4-inch thickness for even cooking.
In a shallow dish, combine the Panko breadcrumbs, grated Parmesan cheese, garlic powder, onion powder, Italian seasoning, 1/2 teaspoon salt, 1/4 teaspoon pepper, and the zest of one lemon. Stir to combine.
In a separate small bowl, mix the mayonnaise with a small pinch of salt and pepper. Brush a thin, even layer of the mayonnaise mixture over all sides of each chicken breast.
Press each mayonnaise-coated chicken breast firmly into the Panko-Parmesan mixture, ensuring a generous and even coating on all sides. Place the crusted chicken in the center of the prepared sheet pan.
Drizzle the tops of the chicken with the remaining 2 tablespoons of olive oil to ensure a golden, crispy crust.
Bake for 20-25 minutes, or until the chicken is cooked through and the juices run clear. The internal temperature should reach 165°F (74°C). The crust should be deep golden-brown and the green beans tender-crisp.
Remove the pan from the oven and let the chicken rest for 5 minutes. Squeeze the warm, roasted lemon wedges over the chicken and green beans just before serving.