01 - Preheat oven to 425°F (220°C). Position the rack in the center of the oven.
02 - Pat the chicken breasts thoroughly dry with paper towels. Combine the kosher salt, black pepper, smoked paprika, and dried oregano in a small bowl, then 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. Place the seasoned chicken breasts in the skillet and sear for 2–3 minutes per side until a deep 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 4–5 minutes, stirring occasionally, until the vegetables begin to soften and pick up color from the fond.
05 - Return the seared chicken breasts to the skillet, nestling them down among the sautéed vegetables. Sprinkle with crushed red pepper flakes if desired for a touch of heat.
06 - Transfer the skillet to the preheated oven. Roast for 15–18 minutes, or until the chicken registers an internal temperature of 165°F (74°C) and the peppers are fork-tender.
07 - Carefully remove the skillet from the oven. Scatter freshly chopped parsley over the top and serve immediately while hot.