Steps
1. Preheat the oven to 375°F (190°C).
2. Cut a pocket into the side of the chicken breast and stuff it with the diced apple and chopped nuts. Season the chicken with salt and pepper.
3. Heat olive oil in a skillet over medium heat. Add the stuffed chicken breast and cook for about 3-4 minutes on each side, until browned.
4. Transfer the chicken to a baking dish and bake in the preheated oven for about 15-20 minutes, or until cooked through.
5. Meanwhile, prepare the mushroom and nut sauce. In the same skillet, add the sliced mushrooms and diced peppers. Cook until softened.
6. Add the chopped nuts and cook for another minute.
7. Pour in the chicken broth and let it simmer for a few minutes.
8. Stir in the heavy cream and season with salt and pepper. Cook until the sauce thickens slightly.
9. Serve the stuffed chicken breast with the mushroom and nut sauce drizzled on top.