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 until well combined.
03 - Pat the chicken breasts dry with paper towels. Rub them evenly with olive oil, salt, and pepper. Place in the prepared baking dish.
04 - Pour the marinade evenly over the chicken breasts, turning to coat thoroughly. Let marinate for at least 10 minutes at room temperature, or refrigerate for up to 2 hours for deeper flavor penetration.
05 - Bake uncovered for 25 to 30 minutes, or until the chicken is cooked through and juices run clear when pierced. Internal temperature should reach 165°F.
06 - Remove from oven and let the chicken rest for 5 minutes to allow juices to redistribute. Garnish with fresh dill and lemon slices before serving.