01 - Preheat oven to 425°F. Position the rack in the center of the oven.
02 - Pat the chicken breasts dry with paper towels. Combine the kosher salt, black pepper, smoked paprika, and dried oregano in a small bowl. Rub the seasoning blend evenly over both sides of each breast.
03 - Heat 1 tablespoon of olive oil in a large oven-safe skillet over medium-high heat until the oil shimmers. Sear the chicken breasts for 2 to 3 minutes per side until a golden crust forms. Transfer the chicken to a plate and set aside.
04 - Add the remaining 1 tablespoon of olive oil to the same skillet. Toss in the sliced bell peppers, red onion, and minced garlic. Sauté for 4 to 5 minutes, stirring occasionally, until the vegetables begin to soften but still retain some bite.
05 - Return the seared chicken breasts to the skillet, nestling them down into the vegetables. Sprinkle with crushed red pepper flakes if desired.
06 - Transfer the skillet to the preheated oven. Roast for 15 to 18 minutes, or until the chicken reaches an internal temperature of 165°F and the peppers are tender.
07 - Remove the skillet from the oven. Let the chicken rest for 3 to 5 minutes, then garnish with fresh chopped parsley and serve immediately while hot.