Preheat oven to 375 degrees F. Take each chicken breast and slice lengthwise but not all the way through. You just want to create a pocket.
In a medium bowl, combine Mozzarella cheese, pesto and chopped tomato. Stir to combine. Divide this mixture evenly among the chicken breasts and stuff it inside each pocket.
In a separate medium bowl, combine Italian dressing, Parmesan cheese, Italian seasoning and red pepper flakes. Take each chicken breast, and holding together to keep stuffing inside, dip each chicken breast into the dressing mixture. Coating each side.
Heat a cast iron skillet or ovenproof skillet over medium high. Add 2 Tablespoons oil to heat. Place chicken breasts inside and sear each side for 3 minutes.
Place skillet in oven and bake for 20 to 25 minutes or until chicken is thoroughly cooked.
Carefully remove from oven and serve warm. Enjoy!