Roast Lamb Leg with Gravy

Bahan-bahan (6 porsi)

• 2.75 - 3 kg / 5.5 - 6 lb lamb leg (, bone-in (Note 1))
• 1 1/2 tsp cooking salt
• 1/2 tsp black pepper
• 1 1/2 tbsp fresh rosemary leaves (, finely chopped)
• 3 g arlic cloves (, finely minced)
• 2 tbsp olive oil
• 2 whole heads of garlic (, halved horizontally (Note 2))
• Few sprigs rosemary ((optional))
• 4 tbsp flour (, plain/all purpose)
• 2 1/2 cups beef broth / stock (, low sodium (Note 3))