In a Dutch oven or large pot, heat the olive oil over medium heat. Add the bay leaves and garlic, sautéing until the garlic softens.
Increase the heat to high, add the lamb and peperoncino, and brown for about 5 minutes. Remove the lamb and set aside.
In the same pan, reduce to medium heat and add the onion, carrots and celery. Cook until the vegetables have softened, about 10 minutes.
Return the lamb to the pan. Pour in the wine and allow the alcohol to evaporate. Season with salt and pepper.
Add the tomato passata and broth. Bring to a simmer, cover, and cook on low heat for about 1 hour, or until the lamb is tender. Stir occasionally and add more broth, passata or water if the sauce thickens too much.
In the meantime, bring a large pot of water to a boil add salt and bring to a boil again. Add the malloreddus and cook until al dente, according to package instructions. Drain and reserve one cup of pasta water.
Add the cooked malloreddus to the lamb ragu. If the sauce is too thick, adjust the consistency with the reserved pasta water. Sprinkle with grated Pecorino Romano cheese and mix well.
Serve hot, with additional Pecorino on the side if desired.