In a medium bowl, place 1/2 cup of mozzarella, all of the ricotta, Italian seasoning, and salt. Stir until well blended and then set aside.
Place chicken on a cutting board and carefully slice 3/4 of the way through the side with a sharp knife. An easy way to do this is to hold the chicken breast down with the flat end of a spatula. Be careful not to cut all the way through as your goal is to create a pocket.
Heat about two tablespoons or so of olive oil in a large skillet over medium high heat.
Stuff cheese mixture into the pocket of each chicken breast. Season the chicken breasts with garlic powder, and salt and pepper.
Place chicken in heated skillet and allow to cook for about five minutes before flipping to the other side and cooking for another five minutes.
Remove from heat and spoon marinara sauce over each chicken breast. Sprinkle the remaining mozzarella cheese over the top of this.
Place in 450 oven for 10-15 minutes, or until chicken is cooked through. If your skillet isn't oven safe, just transfer them to an 8x8 baking dish and place that in the oven instead.