Preheat the oven to 375 degrees F.
In a cast iron fry pan heat about 3 tablespoons of olive oil. Add the green peppers, onions, mushrooms, garlic and saute until veggies are tender about 10 to 15 minutes.
While the vegetables are sauteing prepare the chicken by cutting them butterfly style. Open up the chicken breast and season with salt, pepper, and Italian seasoning.
Divide the vegetables between the two chicken breast and top with two slices of provolone cheese. Bring the top part of the chicken breast over the top of the vegetables. Secure the cut side with toothpicks.
Season the top of the chicken with salt, pepper, and Italian seasoning. Place the chicken into the cast iron skillet season side down. Season the top of the chicken as you did the bottom side.
Brown both sides of the chicken about 1 1/2 per side. Place the cast iron skillet in the oven and bake the chicken for about 15 minutes until the cheese is melted and the chicken is no longer pink.