Place the chicken legs on a roasting tray and drizzle with lemon juice, then rub with salt, pepper, chilli flakes, crushed garlic, and olive oil.
Add chopped rosemary sprigs and set aside to marinade for about 1 hour.
Preheat the oven to 350°F (180°C). Place the chicken in the oven and bake the chicken for 25 minutes, then turn over and bake for a further 20 minutes until golden brown. Once cooked, pour the roast juices over the chicken.
Divide the chicken into 6 portions and serve immediately with your favourite side dishes, e.g. potatoes, salad.