Preheat the oven to 475°F (246°C). Line a rimmed baking sheet with parchment paper.
Arrange the tomatoes on the prepared baking sheet, cut-side up. Drizzle a little olive oil onto each tomato half and season with salt. Bake until the tops of the tomatoes start to caramelize slightly, about 15 minutes.
Meanwhile, place the bread in a food processor and pulse to create fine crumbs. Add the herbs, lemon zest, Parmesan, and olive oil and pulse to combine.
Remove the tomatoes from the oven and spoon the crumbs generously onto the tomato halves. Bake until the crumbs are well toasted, about 15 minutes. Serve warm.