Set a large cast iron skillet over medium heat. Add 2 tablespoons of oil to the skillet. Salt and pepper the chicken on both sides. Once the oil is hot, placed the chicken in the skillet and pan-fry for 5 minutes per side.
Meanwhile, cut (or tear) the prosciutto into pieces. Then seed the bell peppers and cut them into long half-inch strips. Slice the onions and mince the garlic.
Once the chicken breasts have cooked for a total of 10 minutes, move them to a holding plate.
Add the remaining 2 tablespoons of oil to the skillet. Then place the prosciutto in the skillet and sauté for one minute. Add in the sliced peppers, onions, and garlic. Sauté for 3-5 minutes to soften.
Once the onions are soft, pour in the diced tomatoes with juices, chicken broth, balsamic vinegar, Italian seasoning, capers, and crushed red pepper. Bring to a simmer.
Place the chicken breasts back in the pan sauce. Simmer another 2 to 3 minutes to warm the chicken. Then turn off the heat and sprinkle with fresh parsley. Serve warm.
