Season the beef with some salt and pepper then heat the oil in a large heavy based pan over medium-high heat. Once hot add the beef and cook for a couple of minutes on each side to seal all over. Place the beef into the slow cooker.
Now add garlic, onions, celery, and carrots to the saucepan, again over medium-high heat. Sauté, stirring, until soft, around 5 minutes.
Add the wine and continue to saute until the liquid has almost disappeared (1 minute or so). Add the tomato paste, tomato puree and beef stock and stir through. Bring it to a simmer.
Now add the rest of the ingredients; oregano, sugar, pepper, salt, bay leaves and milk. Stir well to combine.
Pour the mixture over the top of the beef in the slow cooker and cook on low for 6-8 hours, mixing it around every so often. It's ready when the beef starts falling apart with a fork and not much pressure.
Place the chunks of meat on a chopping board and use 2 forks to pull it apart. Return it to the slow cooker and mix well.
Bring a large pot of water to a boil. Season with salt; add pasta and cook, stirring occasionally, until just al dente. Drain quickly, reserving ½ cup of the pasta water.
Add the pasta straight to the ragu, and toss to coat. Stir in some of the reserved pasta water by tablespoonfuls if sauce seems dry. Divide pasta among warm plates. Sprinkle with grated parmesan and fresh parsley.