Preheat oven to 350°F. Mix tomatoes, garlic, 2 1/2 tablespoons chives, and Marsala in bowl to blend; season to taste with salt and pepper. Transfer to 8-inch-diameter gratin dish with 1 1/2-inch-high sides.
Mix breadcrumbs, cheese, and olive oil in large bowl to blend. Season topping to taste with salt and pepper. Sprinkle topping over tomatoes. Bake until juices bubble and topping is golden brown, about 40 minutes. Let stand 10 minutes. Sprinkle with remaining 1/2 tablespoon chives and serve.
