Preheat the oven to 450°F. Arrange the hen halves in a single layer, skin side up, on a baking sheet. Brush the skin with 1 tablespoon of the olive oil and sprinkle with salt and pepper. Roast the hens until an instant-read thermometer inserted into the thickest part of the high registers 170ºF, 30 to 35 minutes
Meanwhile, in a bowl, whisk the vinegar and remaining 6 tablespoons olive oil together. Add the bread crumbs, parsley, scallion, anchovies, capers, lemon zest, garlic, thyme, and rosemary and toss together. Season with salt and pepper.
Remove the hens to a platter, top with the toasted bread crumb mixture, and serve immediately.