Step 1: Preheat your oven to 400°F (200°C). Lightly grease a large baking dish with cooking spray.
Step 2: Use a sharp knife to cut a horizontal pocket into the thickest part of each chicken breast. Be careful not to cut all the way through to the other side.
Step 3: Stuff each pocket with one slice of mozzarella cheese. If necessary, secure the opening with two or three toothpicks to prevent the cheese from leaking.
Step 4: Season the outside of the chicken breasts with salt, pepper, and garlic powder.
Step 5: Prepare three shallow bowls for the breading station. Place flour in the first, beaten eggs in the second, and a mixture of Panko, Italian breadcrumbs, and Parmesan in the third.
Step 6: Dredge each stuffed chicken breast in flour, then dip in the egg wash, and finally coat thoroughly in the breadcrumb mixture, pressing gently to adhere.
Step 7: Heat olive oil in a large oven-safe skillet over medium-high heat. Sear the chicken for 3-4 minutes per side until golden brown.
Step 8: Transfer the chicken to the prepared baking dish (or keep in the skillet if oven-safe). Top each breast with a generous spoonful of marinara sauce and a sprinkle of extra cheese if desired.
Step 9: Bake for 15-20 minutes, or until the internal temperature of the chicken reaches 165°F (74°C).
Step 10: Remove toothpicks carefully before serving. Garnish with fresh herbs and enjoy your stuffed chicken parmesan recipe!