In a large heated cast iron skillet, or in a slow cooker with a searing function, add 1-2 tablespoons of olive oil. Season the lamb with salt and pepper, then add to the skillet or slow cooker in batches, over medium-high heat. Brown on at least 2 sides, about 3 minutes per side. Remove from the skillet or slow cooker.
Add the remaining olive oil, followed by the onion, carrots, and celery with some salt. Cook until caramelized, about 5 minutes, then stir in garlic, 1 teaspoon of smoked paprika (optional), ½ teaspoon of red pepper flakes, and 4 tablespoons of tomato paste, cooking until the color of the tomato paste deepens, about 5 minutes.
Add back the cooked lamb, followed by the crushed tomatoes, 1 cup of beef broth, 1 cup of red wine, the herb bundle, bay leaves, and more salt and pepper. Cook on low for 6-8 hours, or on high for 3-4 hours.
Once the lamb is incredibly tender, remove the herb bundle, and bay leaves and discard. Stir in the optional ½ cup of heavy cream, and serve with your pasta of choice. Top with parmesan cheese and basil. Enjoy!
Store leftovers in an airtight container for up to 5 days. Reheat gently on the stovetop or in the slow cooker.