Place chicken breasts between plastic wrap or in a zip-top bag. Pound to an even thickness using a meat mallet.
Season both sides and inside with salt, pepper, garlic powder, and Italian seasoning.
In a bowl, mix ricotta, mozzarella, parmesan, egg, and basil until smooth.
Spoon filling into each chicken breast. Add a spoonful of marinara and a few mozzarella cubes or shredded mozzarella. Do not overfill. Secure with toothpicks if needed.
Dip each stuffed chicken breast into beaten eggs, then coat in breadcrumb and parmesan mixture, pressing firmly to adhere.
Heat olive oil in a large skillet over medium heat.
Carefully place chicken into the skillet and cook for 2–3 minutes per side until golden brown. (Do not cook through.)
Transfer chicken to a greased baking dish.
Bake at 375°F for 20–25 minutes, or until chicken is fully cooked through.
Remove from oven and top with marinara sauce and shredded mozzarella.
Return to oven for 5–10 minutes, until cheese is melted and bubbly.
Let rest for a few minutes, then remove toothpicks, slice, and serve.