Whisk together all the ingredients for the dressing in a small bowl, set aside.

Butterfly two chicken breasts. Put the chicken in a bowl. Toss with salt, pepper, rosemary, crushed garlic, lemon juice and 1/4 cup of the dressing. Let it marinade for 20-30 minutes.

After the chicken has marinaded, heat a tbs olive oil in a large cast iron skillet over medium heat. When skillet is hot, add the chicken and the marinade and cook for about 2 minutes. Flip and cook for 2 minutes on the other side. Cover and bake in a 350 degree oven for 25 to 30 minutes or until chicken is cooked through. Remove from oven and let rest at room temperature.

While the chicken is resting, chop the head of romaine into 1 inch pieces. Put it in a large bowl. Top chopped lettuce with halved cherry tomatoes, onions and cubed fresh mozzarella. Set aside.

When the chicken has rested for 10 minutes, cut on a bias against the grain into strips. Add to the top of the salad. Sprinkle chopped walnuts on top to finish. Serve with reserved dressing.