Preheat the oven to 425 degrees F. Heat 3 tablespoons olive oil in a large pot or Dutch oven over medium-high heat. Add the tomato paste and cook, stirring, until slightly darkened, about 2 minutes. Add the rosemary, garlic and red pepper flakes and cook until the garlic starts browning, about 1 minute.
Add the green beans, cherry tomatoes and their liquid, 1 3/4 cups water and 2 teaspoons salt to the pot. Partially cover and cook, stirring occasionally, until the green beans are tender and the liquid is slightly thickened, 20 to 25 minutes. Transfer to a 3-quart baking dish.
Mix the panko, parmesan, parsley and the remaining 2 tablespoons olive oil in a bowl; season with salt and pepper. Sprinkle over the green bean mixture and bake until the sauce is bubbling and the topping is browned, about 15 minutes.
Photograph by Ryan Dausch