Chicken

1. Preheat your oven to 200°C (400°F).
2. Melt butter in a large, oven-proof skillet (12-inch or 30 cm) over medium heat. Add garlic and sauté until fragrant (about 1 minute). Add mushrooms, salt, pepper (to taste), and parsley. Cook while stirring occasionally until soft. Set aside and allow to cool while preparing your chicken.
3. Pat chicken breasts dry with a paper towel. Season with salt, pepper, onion powder, and dried parsley. Rub each piece to evenly coat in seasoning.
4. Horizontally slice a slit through the thickest part of each breast to form a pocket. Place two slices of mozzarella into each pocket.
5. Divide the mushroom mixture into four portions and fill each breast (leave the juices in the pan for later). Top the mixture with a tablespoon of parmesan cheese per breast. Seal with toothpicks to keep the mushrooms inside while cooking.
6. Heat the same pan along with the pan juices (the garlic butter will start to brown and take on a nutty flavor). Add the chicken and sear until golden. Flip and sear the other side until golden. Cover the pan and continue cooking in the oven for another 20 minutes or until completely cooked through.
7. Serve with pan juices and any remaining mushrooms over pasta, rice, or steamed vegetables.

Optional Cream Sauce

1. Fry garlic in the leftover pan juices until fragrant (about 1 minute). Reduce heat to low and add mustard and half and half (or cream).
2. Bring the sauce to a gentle simmer and add any remaining mushrooms and parmesan cheese. Simmer until the parmesan melts slightly.
3. If the sauce is too thin, add the cornstarch mixture and stir through quickly.
4. Season with salt and pepper to taste. Add parsley and return the chicken to the pan.
5. Serve and enjoy!