- With the rack in the middle position, preheat the oven to 350°F (180°C).
- In a large pot over medium-high heat, brown half of the meat at a time in the oil. Season with salt and pepper. Set aside on a plate.
- In the same pot over medium heat, soften the onion, carrot, celery and garlic for 2 minutes. Add the tomato paste and cook 1 minute while stirring. Deglaze with the wine and let reduce by half. Return the meat to the pot and add the veal stock. Bring to a boil and cover.
- Transfer to the oven and cook for 2 hours or until the meat is tender. Remove from the oven. Shred the meat by pressing on it with a wooden spoon.
- Meanwhile, in a small bowl, combine the Parmesan, parsley and lemon zest. Set aside.
- In a large pot of salted boiling water, cook the squash for 5 minutes. Remove the squash with a slotted spoon and add to the pot of beef.
- In the same pot of boiling water, cook the pasta until al dente. Reserve 1 cup (250 ml) of the cooking water. Drain the pasta and add to the pot of beef. Add 1/2 cup (125 ml) of the cooking water and half the Parmesan mixture. Reheat everything for 1 minute, stirring to coat the pasta in the sauce. Add more cooking water, if desired. Adjust the seasoning. Divide among four plates and garnish with the remaining Parmesan mixture.