Follow these steps to create your delicious Rosemary Braised Lamb Shanks with Creamy Polenta:

1. Prepare the Lamb: Season the lamb shanks generously with salt and pepper.
2. Sear the Lamb: In a large Dutch oven, heat olive oil over medium-high heat. Sear the lamb shanks for about 4-5 minutes on each side until browned. Remove shanks and set aside.
3. Sauté Vegetables: In the same pot, add onions, carrots, and celery. Sauté for about 5-7 minutes until soft. Add minced garlic, rosemary, and thyme, cooking for an additional 1-2 minutes.
4. Deglaze the Pot: Pour in the red wine, scraping the bottom to release any caramelized bits. Let it simmer for 2-3 minutes until reduced slightly.
5. Add Remaining Ingredients: Stir in the diced tomatoes, broth, and bay leaf. Place the lamb shanks back into the pot, ensuring they are mostly submerged in liquid.
6. Braise the Lamb: Bring the liquid to a boil, then cover the pot and reduce the heat to low. Let the lamb braise for 2-2.5 hours, or until fork-tender.
7. Prepare the Polenta: In a separate saucepan, bring 4 cups of water to a boil. Slowly whisk in the polenta, and reduce heat to low. Cook, stirring frequently, for about 30-40 minutes until creamy.
8. Finish the Polenta: Stir in heavy cream and Parmesan cheese, mixing until smooth. Season with salt and pepper to taste.
9. Serve: Once the lamb is tender, remove from heat and discard the bay leaf. Serve the lamb shanks on a bed of creamy polenta, garnishing with fresh parsley if desired.