In a skillet, heat the olive oil over medium heat. Grasp the shoulder for 2 to 3 minutes on each side. Add the onion with the pancetta, carrots, celery and cook for 2 to 3 minutes.
Add the herbs with the garlic and cook for 1 minute. Pour in the wine and add the diced tomatoes, passata and broth.
Bring to a boil, cover and cook in the oven for 2 hours 30 minutes to 3 hours, until the meat is tender and flakes easily with a fork.
Remove the shoulder to a plate and shred the flesh using 2 forks.
Return the flesh to the skillet, stir and simmer for 2 to 3 minutes over medium low heat.
In a saucepan, bring the milk to a boil with the broth. Pour in the polenta, whisking constantly. Simmer over low-medium heat for 2 to 3 minutes, stirring constantly with a wooden spoon. Add the parmesan, salt and pepper.
On a bed of polenta serve the shredded lamb and garnish with parsley.