Sprinkle the small chicken breast with salt and pepper on both sides. Heat a large skillet over medium high heat with olive oil. Add the chicken and cook for about 3-4 minutes per side or until the chicken is cooked thoroughly. Remove to a plate and set aside while cooking the sauce.
Using the same pan that you cooked the chicken in, add the onion and cook for 2-3 minutes. Then add the garlic and saute for 30 seconds. Add the crushed tomatoes, Italian seasoning, red pepper flakes, dried basil, and pesto. Stir to combine. When the sauce starts to simmer, add the water, lower the heat, and cover. Allow the sauce to simmer for about 10 minutes until it thickens. Salt and pepper to taste.
While the sauce is thickening, cook the pasta according to the box instructions. Place the cooked chicken breast back into the pan with the sauce. Cover each chicken breast with a spoonful of sauce and cover with a slice of cheese. Place under the broiler for 2 minutes or until the cheese melts. Top with chopped parsley. Serve over cooked pasta.