Place the chicken breasts between two pieces of parchment paper or plastic wrap on a level work surface. Firmly pound each breast with the smooth side of a meat mallet to a thickness of ½ inch. Set aside.
Place the eggs, parsley, garlic, salt, and pepper in a shallow bowl and whisk until combined. Set aside.
In a second shallow bowl, combine the breading (or crushed pork rinds) and Parmesan cheese. Set aside.
In a very large skillet with a lid over medium-high heat, warm 2 tablespoons of the oil.
One at a time, dip four of the chicken breasts in the egg mixture and then in the breading mixture. Once they are fully coated, place them in the skillet.
Cook the chicken for 4 to 5 minutes on each side, or until nicely browned. Remove from the skillet and set aside on a plate.
Warm the remaining 2 tablespoons of oil in the skillet and repeat process with the remaining four chicken breasts. Remove cooked chicken to the same plate.
Reduce the heat to low. Deglaze the skillet with the marinara sauce, stirring and scraping the bottom of the pan. Return all of the chicken to the skillet, cover and cook for 5 to 8 minutes, or until an instant-read thermometer inserted in the thickest part of the breast, registers 165 degrees F. Remove from the heat.
Spoon the sauce over the chicken and sprinkle equal portions of the mozzarella cheese over each breast. Cover to let cheese melt for 1-2 minutes. Garnish with additional parsley and enjoy!