Start by prepping all your veg: peel and finely chop the onions, garlic and carrots, trim and finely slice the celery, then peel, deseed and finely chop the squash. Finely slice the bacon. Heat the oil in a very large casserole pan over a medium-low heat, add the bacon, followed by the onion, garlic, carrot, celery and squash and cook gently for about 15 minutes, or until soft. Add the mince, breaking it up with a spoon, and cook for about 10 minutes. Turn the heat up, pour in the wine and leave to bubble and cook away for a few minutes, then tip in the tomatoes and 2 tins' worth of water. Drop in the rosemary sprigs and bay leaf, and season with sea salt and black pepper. Bring to the boil, then cover and simmer for 1½ hours. After this time, if the ragù is still quite liquidy, remove the lid, turn the heat up and simmer for a few more minutes, or until thickened and reduced. Eat straight away, or if you’re making this ahead of time, allow to cool, then divide between containers or plastic freezer bags.