If using full boneless chicken breasts, use a thin, sharp knife to slice the chicken breast in half lengthwise to make two thinner scallops. Pat the cutlets with a paper towel then season both sides with 1 teaspoon kosher salt and ½ teaspoon black pepper. Set aside.

Add the tomatoes and sliced zucchini to a bowl and drizzle with 1 tablespoon of olive oil. Season with the rest of the kosher salt and black pepper and toss to coat.

Bring a large heavy bottom skillet or cast iron pan to medium-high heat. Add 1 tablespoon of olive oil to the skillet. Add the tomatoes and zucchini to the pan and cook for 2-3 minutes or until the zucchini just begins to soften and a few tomatoes start to burst. Give the veggies a stir and a flip as they cook. Transfer to a pan and cover to keep warm.

Add the remaining olive oil and butter to the skillet to melt. Add the chicken cutlets and cook undisturbed for 4-5 minutes or until golden brown on the bottom side. Flip and cook for another 2-3 minutes. Dollop and spread a few tablespoons of the pesto onto the chicken breasts. You'll likely have extra so save for another use. Tear the fresh mozzarella into pieces and top each of the chicken breasts with the cheese. Add the reserved tomatoes and zucchini back into the skillet, nestling around the chicken. Set the heat to low and cover with a lid. Warm the dish until the mozzarella is melted. Garnish with fresh basil leaves and more black pepper if desired.