In a large saucepan, stir together the onion, garlic and lamb. Break the meat down with a spatula. Cook gently for 2-3 mins until the lamb is sealed.
I like to drain any fat away, but it's not necessary. Add the tomato puree, tomatoes, stock, mint and Worcestershire sauce. Season well and bring to the boil. Add the carrots, courgettes and mushrooms, reduce the heat and simmer for 20mins (or until the veg is how you like it).
In the meantime, cook the pasta in boiling salted water according to the packet instructions.
Drain the pasta well and spoon into bowls, spoon the lamb sauce over the pasta and serve immediately topped with grated cheese.