Preheat your oven to 425°F (220°C). Place the whole red bell peppers on a baking sheet and roast them in the preheated oven until the skins are charred, about 25-30 minutes. Remove from the oven and place in a bowl, covering it with plastic wrap to steam. After 10 minutes, peel the skins off and slice the peppers into strips.
Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Season the chicken breasts with salt, pepper, smoked paprika, and oregano. Once the oil is hot, add the chicken breasts and sear them for about 5-6 minutes on each side until browned. Remove the chicken from the skillet and set aside.
In the same skillet, add the diced onion and minced garlic. Sauté for 2-3 minutes until softened and fragrant. Then, add the red pepper flakes (if using) and continue to cook for another minute.
Pour in the chicken broth and add the roasted red pepper strips to the skillet, stirring to combine. Carefully place the seared chicken breasts back into the skillet, coating them in the sauce.
Transfer the skillet to the oven (if it's oven-safe) or place everything into a greased baking dish. Bake for 15-20 minutes, or until the chicken is cooked through (a thermometer should read 165°F or 75°C).
Once cooked, remove from the oven and let it rest for a few minutes. Garnish with fresh basil leaves before serving.
Notes
Adjust red pepper flakes to taste for desired spiciness.