Ingredients:
* 4 boneless, skinless chicken breasts (about 1 1/2 lbs)
* 1 tablespoon olive oil
* Salt and pepper to taste
* 1 tablespoon butter
* 1/2 cup chopped onion
* 1/2 cup chopped mushrooms
* 1/4 cup chopped fresh parsley
* 1/4 cup grated Parmesan cheese
* 1/4 cup crumbled blue cheese
* 1/2 cup panko bread crumbs
Instructions:
* Preheat oven to 400°F (200°C).
* Pound the chicken breasts: Place each chicken breast between two sheets of plastic wrap and gently pound to an even thickness. Season with salt and pepper.
* Sauté the vegetables: Heat olive oil in a skillet over medium heat. Add onion and cook until softened, about 5 minutes. Add mushrooms and cook until softened, about 5 minutes more. Stir in parsley and set aside.
* Make the stuffing: In a bowl, combine Parmesan cheese, blue cheese, and panko bread crumbs. Stir in the sautéed vegetables.
* Stuff the chicken: Make a shallow cut horizontally in each chicken breast. Fill each cavity with the mushroom mixture.
* Bake the chicken: Arrange the stuffed chicken breasts in a baking dish. Bake for 20-25 minutes, or until the chicken is cooked through and the stuffing is golden brown.
* Serve and Enjoy: Let the chicken rest for a few minutes before slicing and serving.