Warm a large heavy pot over medium heat then add olive oil.
Add sausage and cook until browned breaking it into small bits then scoop to a bowl.
In the same pot add onion celery and carrots with a pinch of salt then cook until soft.
Stir in garlic and tomato paste and cook until the paste turns deep red.
Pour in wine to deglaze and scrape the pot then simmer until most liquid cooks off.
Return sausage to the pot then add crushed tomatoes stock parmesan rind rosemary thyme and bay leaf.
Bring to a gentle simmer then cook uncovered and stir now and then for 45 to 60 minutes until thick and glossy.
Fish out the herb stems rind and bay leaf then stir in milk.
Boil pasta in salted water until al dente then reserve a cup of pasta water and drain.
Toss pasta with sauce and a splash of pasta water then cook one minute and season with salt and pepper.
Finish with grated parmesan and red pepper flakes then serve hot.