Cut each breast in half and pound the pieces to 1/4-inch thickness. Combine the flour and black pepper in a small bowl. Dip the chicken into the flour and coat each piece thoroughly. In a large skillet over medium heat, saute the chicken in the oil until brown, about 5 minutes on each side.
Transfer the chicken to a plate. Add the garlic, peppers and onions to the skillet, and saute the vegetables until they are tender. Return the chicken to the skillet. Add the tomatoes and zucchini. Heat the mixture to boiling. Reduce the heat to low, cover the skillet and simmer for 15 minutes. Top the chicken with mozzarella and Parmesan,and simmer until the cheese melts.