Brown the Lamb: Heat the olive oil in a large large, heavy-bottomed pan over medium-high heat. Sprinkle the lamb cubes with pepper and salt, then grill them in groups until golden on both sides. Take them off and place them aside.

Sauté the vegetables: Within the pan lower the temperature to medium-low and add chopped onions and carrots, as well as celery and garlic. Cook until the vegetables are tender and aromatic, approximately 7 to 7 minutes.

Add the tomatoes and broth: Stir in the crushed tomatoes, the broth bay leaf, and rosemary. The lamb is then returned to the pan and make sure that the meat is fully submerged in the sauce.

Simmer low and slow: Bring the mixture to a low simmer then cover and lower the heat to a simmer. Allow it to cook for about 2 hours, while stirring frequently until the lamb is soft and falls into pieces. If the gravy becomes too thick, try adding some broth or water.

Season and serve: Taste the ragu and then adjust the seasoning using the addition of salt or pepper. Serve the ragu with freshly cooked pasta. decorate with grated Parmesan and fresh basil, if wanted.