Preheat oven to 425°F (220°C). Slice each chicken breast in half lengthwise to make 8 thin cutlets. Pound each to about ⅛ inch thick. Season both sides with garlic salt and black pepper.

Spread 1 tablespoon pesto in the center of each cutlet. Top with 2 tomato slices and sprinkle with 2-3 tablespoon mozzarella. Roll tightly and secure with toothpicks.

Heat olive oil and butter in a large oven-safe skillet over medium-high heat. Sear roll-ups 4 minutes per side until golden brown.

Sprinkle remaining mozzarella on top. Add cherry tomatoes around chicken if using. Transfer skillet to oven and bake 13-15 minutes until internal temp reaches 160°F.

Garnish with fresh basil. Serve hot.