- Heat oven to 400° F. In a food processor, pulse the bread until coarse crumbs form (you should have about 2 cups). Add the pecorino, butter, ½ teaspoon salt, and ¼ teaspoon pepper and pulse once or twice to moisten.
- Place the chicken in an 8-inch baking dish; season with ½ teaspoon salt and ¼ teaspoon pepper and sprinkle with the bread crumb mixture. Cover with foil and bake until cooked through, 15 to 20 minutes. Uncover and bake until crumbs are golden, 3 to 5 minutes.
- Meanwhile, heat the oil in a large skillet over medium-high heat. Add the chard, ½ teaspoon salt, and ¼ teaspoon pepper. Cook, tossing, until tender, 3 to 4 minutes. Serve with the chicken.