Prepare the Chicken: Butterfly each chicken breast by slicing horizontally almost all the way through, then opening it like a book. Season the inside and outside with salt, pepper, garlic powder, and onion powder.

Make the Stuffing: In a medium bowl, combine the softened cream cheese, Gruyere cheese, Parmesan cheese, heavy cream, parsley, and minced garlic. Mix until well combined and creamy.

Stuff the Chicken: Divide the cheese mixture evenly among the chicken breasts, spreading it over one side of each breast. Fold the other side over the filling, creating a stuffed chicken breast. Secure with toothpicks if needed.

Sear the Chicken: Heat the olive oil in a large oven-safe skillet over medium-high heat. Sear the stuffed chicken breasts for 2-3 minutes per side, until lightly golden brown. This step adds flavor and helps to seal in the juices.

Bake the Chicken: Transfer the skillet to a preheated oven at 375°F (190°C). Bake for 20-25 minutes, or until the chicken is cooked through and the internal temperature reaches 165°F (74°C). The cheese filling should be melted and bubbly.

Rest and Serve: Remove the skillet from the oven and let the chicken rest for 5-10 minutes before removing the toothpicks and serving. Serve hot with your favorite sides.