01 - Preheat the oven to 400°F. Lightly grease a baking dish with olive oil.
02 - In a small bowl, whisk together lemon zest, lemon juice, dill, garlic, Dijon mustard, onion powder, and red pepper flakes.
03 - Pat the chicken breasts dry. Rub them with olive oil, salt, and pepper. Place in the prepared baking dish.
04 - Pour the marinade evenly over the chicken breasts, turning to coat well. Let marinate for at least 10 minutes, or up to 2 hours in the refrigerator for deeper flavor.
05 - Bake uncovered for 25–30 minutes, or until the chicken is cooked through and juices run clear, reaching an internal temperature of 165°F.
06 - Remove from oven and let rest for 5 minutes. Garnish with fresh dill and lemon slices before serving.