Saute garlic and leeks in a large saucepan until the house is filled with that heavenly garlic aroma.
Add the pureed tomatoes, crushed whole tomatoes, basil, rosemary, oregano, and fresh cracked pepper. Let that simmer on very low while preparing the chicken.
Combine two tablespoons of olive oil, a teaspoon of ground garlic, and 8-10 chopped fresh basil leaves in a small bowl. Mix well.
Slice the Mozzarella into 8 slices.
Take each chicken breast and cut a deep pocket in the middle of the thickest part of the breast for the filling with a sharp knife, careful not to cut all the way through. Season the outside of the chicken breasts with pepper.
Spread a teaspoon of the filling inside the chicken pocket. Then add 1-2 slices of mozzarella cheese. Close the pouch and seal it with toothpicks.
Add one to two tablespoons of olive oil to a large skillet over medium heat. Add the chicken to the hot pan and saute the stuffed chicken breasts until lightly golden on each side – about 3-4 minutes per side.
Place the chicken breasts in the tomato sauce and spoon the sauce over the breasts. Let the chicken cook on a low simmer, loosely covered, for about 25 minutes until the chicken breasts reach 160 degrees internal temperature with an instant-read thermometer.
