Finely chop the onion and slice the garlic.
Wash the rice well, drain.
Chop the rosemary leaves.
Shred the chicken meat.
Heat the oil in a heavy-bases saucepan. Add the onion and cook it gently for 5 minutes, until soft then add the pancetta. Cook for another 3-4 minutes until crisp. Add the rosemary and garlic slices. Stir for a minute, then add the rice, stir for another minute, then pour over the stock.
Bring the broth to the boil, then simmer for 15 minutes. When the stock is almost completely absorbed, add the shredded meat. Cook for another 5 minutes (at low temperature and under cover).
When the rice is tender (but still al dente), add the lemon zest & juice, then turn off the heat.
Rest under cover for a couple of minutes. Chop the parsley, add to the rice, season with salt & pepper.
Serve with Parmesan sprinkled on top if you like.