Strozzapreti with Lamb Ragù

In a large enameled cast-iron casserole, combine the fennel, cumin, Aleppo pepper and peppercorns and cook over moderate heat until fragrant, 2 minutes. Let cool, then wrap in cheesecloth and tie into a bundle. Add the oil to the casserole and heat. Add half of the lamb, season with salt and pepper and cook over high heat, breaking it up with a spoon, until browned, 3 minutes. With a slotted spoon, transfer the lamb to a bowl. Repeat with the remaining lamb. Pour off all but 2 tablespoons of the fat from the casserole. Add the garlic, onion and fennel and cook over moderate heat until softened, 8 minutes. Stir in the spice bundle, paprika, harissa, tomatoes and their liquid and the stock. Return the lamb and accumulated juices to the casserole and bring to a simmer. Cover the ragù and simmer over low heat for 45 minutes, stirring occasionally. Uncover and simmer until thickened, about 50 minutes longer. Discard the spice bundle and season the ragù with salt and pepper. In a large pot of boiling salted water, cook the pasta until al dente. Drain and return to the pot. Add the ragù and stir. Fold in the cherry tomatoes, scallions and half of the mint. Season with salt and pepper; transfer to a large bowl. Top with the remaining mint and serve, passing the cheese at the table.