Add the lemon, potatoes, rosemary, and optional garlic to a sheet pan or baking dish. Drizzle with 2-4 tablespoon olive oil, salt and pepper. Toss to coat. Make sure the chicken is well seasoned on both sides.
Cook for 45 minutes. Remove the tray from the oven. Gently squeeze the roasted lemon wedges over everything in the pan.
Cook another ~15 minutes until the chicken is cooked through and the potatoes are toasty.