Heat oil in a large saucepan over medium-high heat. Season lamb shanks and cook, turning occasionally, for 5-7 mins or until browned all over. Transfer to a large bowl. Add mushrooms to same pan. Cook for 5 mins or until tender. Transfer to bowl with lamb.
Add garlic, onion, carrot and celery to pan, adding a little extra oil, if necessary. Cook for 5 mins or until onion softens. Return lamb, mushrooms and any juices to pan. Add passata, stock, thyme, rosemary. Bring to the boil. Reduce heat to low. Cook, covered, for 2-2 ¼ hours or until lamb is falling off the bone, turning shanks occasionally. Use tongs to transfer lamb to a heatproof bowl and coarsely shred lamb using 2 forks. Discard bones. Return lamb to tomato mixture. Stir through kale. Season. Remove thyme stalks.
Meanwhile, cook pasta in a large saucepan of boiling water following packet directions or until al dente. Drain well.
Divide pasta and lamb ragu among serving bowls. Top with parmesan and basil leaves. Serve with baby rocket and lemon wedges.
Tips
Slow cooker option - Follow instructions in recipe to the point where you return lamb, mushrooms and juices to the pan. Instead add all ingredients to slow cooker. Cover and cook on HIGH for 4 hours or on LOW for 7 hours, until lamb is very tender.
Serve leftover ragu with polenta, quinoa or cous cous and your choice of vegetables.
