In a pan, heat olive oil and butter together over low heat with a sprinkle of red pepper flakes. Melt a couple of anchovies over low heat until the smell becomes nutty and pleasant. Add a diced onion and cook until golden brown. Add a pound of Italian pork sausage (minus the casing, i.e. loose) and raise the heat to high, until the sausage is very browned and crispy. Add minced garlic, and cook for 30 seconds to 1 minute.
Add a cup of white wine, stir to deglaze the pan, and allow it to evaporate completely. Add a cup of milk, a half-cup of chicken stock (stock, not broth), a Tb of tomato paste, and reduce heat to low. Season to taste, and simmer for 15 minutes.
Cook pasta al dente. Add a splash of the leftover cooking water to the ragu if it’s getting too “tight”. Add pasta to ragu, toss to combine. Serve with fresh basil and/or Parmigiano-Reggiano.