Step 1: Slice the Chicken Into Thin Cutlets - Place each chicken breast on a sturdy cutting board and carefully slice it through the middle from the side so you end up with two thinner pieces from each breast. You should have about four cutlets total, each close to one half inch thick. I like doing this because thinner chicken is much more forgiving on a busy night. It cooks faster, browns more evenly, and makes it easier to get the center done before the outside dries out.
Step 2: Season the Chicken Evenly - Put the chicken cutlets in a bowl and add the salt, black pepper, Italian seasoning, and one tablespoon of olive oil. Toss everything together until every piece has a light coating of oil and seasoning on both sides. You are not looking for a heavy crust here. The goal is simply to make sure the chicken is seasoned before it ever touches the pan, because that gives you better flavor in every bite instead of relying on the toppings to do all the work.
Step 3: Brown the Chicken in the Skillet - Heat the remaining tablespoon of olive oil in a large skillet over medium heat. Once the oil is warm, add the chicken in a single layer and let it cook for about 5 to 6 minutes on the first side. Flip the pieces and cook for another 5 to 6 minutes, adjusting the heat if the pan gets too hot. You want a golden surface with a little color around the edges. That browning adds a savory depth that makes the fresh tomatoes and creamy cheese taste even better later.
Step 4: Add the Tomatoes and Mozzarella - Scatter about half of the cherry tomatoes around the chicken in the skillet. If some are larger, you can cut them in half so they soften a little faster and release some of their juices into the pan. Lay slices of fresh mozzarella over each chicken cutlet, covering as much of the top as you comfortably can. At this point the skillet starts to look like dinner. The tomatoes warm and soften beside the chicken while the cheese gets ready to melt into a creamy layer.
Step 5: Cover and Melt the Cheese - Place a lid over the skillet and cook for about 4 minutes. The trapped heat helps the mozzarella melt without forcing you to keep cooking the chicken uncovered for too long. Check the thickest part of the chicken with an instant read thermometer if you have one. You are looking for 165 degrees Fahrenheit. Once the chicken is cooked through and the cheese is soft and fully melted, remove the skillet from the heat so the chicken stays juicy.
Step 6: Spoon on the Pesto - Spread about one tablespoon of pesto over each chicken cutlet after the skillet is off the heat. This timing matters more than it may seem. Pesto has fresh basil, garlic, cheese, and olive oil, and those flavors taste brighter when they are warmed by the chicken instead of cooked hard in the skillet. The pesto will loosen slightly against the hot mozzarella and settle into the little curves and edges, giving every forkful a fresh herbal finish.
Step 7: Finish With Fresh Tomatoes and Basil - Top the chicken with the remaining fresh cherry tomatoes and plenty of fresh basil. Add a light sprinkle of grated Parmesan just before serving. I like the contrast here because you get warm tomatoes from the skillet and fresh juicy tomatoes on top, along with soft mozzarella and fragrant basil. Bring the skillet to the table while everything is still warm. It is one of those meals where the colors do half the work of getting everyone interested before you even start serving.