Step 1: Preheat your oven to 400°F (200°C). Use a sharp knife to cut a pocket into the side of each chicken breast, being careful not to cut all the way through.
Step 2: In a small bowl, mix the shredded mozzarella and chopped basil. Stuff about 1/4 cup of the mixture into each chicken pocket and secure with toothpicks if necessary.
Step 3: Set up three shallow bowls for dredging. Place flour in the first, beaten eggs in the second, and a mixture of Panko, Parmesan, garlic powder, salt, and pepper in the third.
Step 4: Dredge each stuffed chicken breast in flour, then egg, and finally the breadcrumb mixture, pressing firmly to ensure an even coating.
Step 5: 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 6: Spoon marinara sauce over each breast and top with a little extra cheese if desired. Transfer the skillet to the oven and bake for 15-20 minutes until the chicken is cooked through.
Step 7: Let the chicken rest for 5 minutes before removing toothpicks and serving.