In a wide heavy-bottomed pot or Dutch oven, heat 2 tbs extra-virgin olive oil and 1 tbs butter over medium-high heat until shimmering. In batches (do not overcrowd), add lamb cubes and sear until deeply browned on all sides, about 6–8 minutes per batch. Transfer browned lamb to a plate and set aside.

Soffritto

Reduce heat to medium. Add remaining 1 tbs olive oil to the pot. Add diced onion, carrot, and celery; cook, stirring occasionally, until softened and beginning to color, about 8–10 minutes. Add minced garlic and cook 1 minute more until fragrant.

Tomato paste and deglaze

Add tomato paste to the vegetables and cook, stirring, 2 minutes to caramelize slightly. Pour in the red wine to deglaze, scraping up browned bits from the pot. Increase heat to medium-high and simmer until the wine is reduced by about half, 6–8 minutes.

Combine and simmer

Return the browned lamb and any accumulated juices to the pot. Add the crushed San Marzano tomatoes, stock, rosemary, thyme, bay leaves, nutmeg, brown sugar (if using), remaining 1 tsp salt and 1/2 tsp black pepper. Stir to combine and bring to a gentle simmer.

Slow cook

Cover the pot partially with a lid (leave a small gap for steam to escape) and reduce heat to low. Simmer gently for 2 to 2.5 hours, stirring every 20–30 minutes, until the lamb is fork-tender and the sauce has thickened. If sauce reduces too much, add up to 100 ml more stock or water as needed.

Shred and finish

Remove bay leaves. Use two forks to shred larger chunks of lamb into bite-sized pieces, leaving some intact for texture. Stir in heavy cream (if using) and 1 tbs extra-virgin olive oil to enrich the sauce. Adjust seasoning with remaining salt and pepper to taste.

Pasta & Serve

Cook the mafalde

Bring a large pot of water to a rolling boil; add 2 tbs salt. Cook mafalde according to package instructions until al dente, usually 9–12 minutes. Reserve 1 cup (240 ml) pasta cooking water, then drain the pasta.

Finish pasta with ragu

Add drained mafalde to the ragu pot off the heat and toss gently to combine, adding a splash of reserved pasta water as needed to help the sauce coat the pasta (start with 2–4 tbs and add more if needed). Cook together over low heat 1–2 minutes so pasta absorbs sauce.

Plate and garnish

Divide pasta among 4 plates. Sprinkle with grated cheese and chopped parsley, finish with a drizzle of extra-virgin olive oil and an optional crack of black pepper. Serve immediately.