Wash and pat dry the chicken breast fillets. Cut in half horizontally if necessary. Heat olive oil over medium-high heat in a large skillet and fry the chicken for 2-3 min per side until lightly browned. Transfer to a baking dish.
Heat olive oil over medium heat in a saucepan. Add the finely chopped garlic cloves and cook for 1 min until fragrant. Pour in the chopped tomatoes and bring to a simmer. Season with salt and simmer for 10 min. Stir in the tomato paste and fresh herbs. Season with salt and pepper.
Pour the tomato sauce over the chicken in the baking dish. Slice the mozzarella and arrange over the chicken. Halve the cherry tomatoes and scatter over the top. Mix the Parmesan with breadcrumbs and sprinkle over. Break the butter into small flakes and scatter over the top.
Bake in a preheated oven at 180°C (350°F) with fan/convection, or 200°C (400°F) without fan, for 20-30 min until the cheese has melted and the topping is golden and crispy. The chicken should reach an internal temperature of 74°C (165°F).