• Start by making the cherry tomato salad topping. Cut the cherry tomatoes in half and add them to a medium bowl with the chopped basil, diced red onion, olive oil, balsamic vinegar, lemon juice, and oregano. Season with kosher salt and black pepper to taste. Toss everything together, then set aside while you prepare the chicken. The tomatoes will become juicier and more flavorful as they sit. 1 pint Cherry Tomatoes 1/4 cup Fresh Basil 1/4 Red Onion 2 tbsp Olive Oil 1 tbsp Balsamic Vinegar 1 tbsp Lemon Juice 1/2 tsp Oregano Kosher Salt Black Pepper
• Pat chicken dry with a paper towel. Place one chicken breast flat on a cutting board. Hold the top of the chicken steady with one hand and, using a sharp knife, carefully slice horizontally through the thickest side of the breast. Stop cutting about ½ inch before reaching the opposite edge so the chicken remains attached. Open the chicken breast like a book. Repeat with the remaining chicken breasts. 4 Boneless Skinless Chicken Breasts
• In a small bowl, combine the Italian seasoning, garlic powder, onion powder, kosher salt, and black pepper. Season both the inside and outside of each butterflied chicken breast, gently pressing the seasoning into the surface. 1 1/2 tbsp Italian Seasoning 2 tsp Garlic Powder 2 tsp Onion Powder 1 tsp Kosher Salt 1 tsp Black Pepper
• Spread 1 tablespoon of pesto over the inside of each chicken breast. Slice the fresh mozzarella into about 1/4 inch slices and place 2-3 slices on one side of each breast, leaving a small border around the edges. Don't add too much, it'll just melt out during cooking. Fold the other side of the chicken over the cheese to close it. 4 tbsp Pesto 8 oz Fresh Mozzarella
• Secure the open edges with toothpicks, sticking them through both sides of the chicken to help keep the mozzarella inside as it cooks. This step is optional, but it makes the chicken easier to flip and helps prevent the cheese from slipping out.

Outdoor Grill Method

• Preheat an outdoor grill to medium heat, about 375–400°F. Clean and lightly oil the grill grates to help prevent sticking.
• Place the stuffed chicken breasts on the grill and close the lid. Cook for 6–8 minutes on the first side, or until the chicken releases easily from the grates and has deep golden grill marks.
• Carefully flip the chicken using a wide spatula or tongs. Grill for another 6–8 minutes with the lid closed. The chicken is ready when the outside is golden and lightly charred, the center is no longer pink, the mozzarella is soft and melted, and the thickest part of the chicken reaches an internal temperature of 165°F.
• Transfer the chicken to a clean plate and let it rest for 5 minutes. Remove the toothpicks before serving.

Grill Pan Method

• Place a grill pan over medium-high heat and allow it to preheat for 3–4 minutes. Lightly brush the pan with olive oil. The pan should be hot enough that the chicken sizzles as soon as it touches the surface, but it should not be smoking heavily.
• Add the chicken breasts to the pan without crowding them. Cook for 6–8 minutes, without moving them too much, until the bottoms are golden brown with visible grill marks.
• Carefully flip the chicken. Reduce the heat to medium-low and cover the pan with a lid or loosely tent it with foil. Cook for another 6–10 minutes, depending on the thickness of the chicken. The chicken is done when it feels firm but still has a slight spring when pressed, the juices run clear, the cheese is melted, and the internal temperature reaches 165°F.
• Transfer the chicken to a plate and let it rest for 5 minutes. Remove the toothpicks before serving (if using).
• Spoon the tomato salad mixture generously over each chicken breast, including some of the juices from the bottom of the bowl. Garnish with additional fresh basil and a drizzle of balsamic glaze, if desired.