Remove the sausage from its casing if needed. Break it into rough irregular pieces by hand instead of mincing it too finely. The sausage should cook into uneven crumbles — some small, some larger. Uniform tiny mince looks boring and eats flat. Irregular pieces give better texture. Breaking the sausage apart unevenly by hand, rather than mincing it into a uniform texture, produces a mix of larger pieces that develop a real seared crust and smaller ones that crisp through more fully — that textural variety is part of what makes the finished ragù interesting bite to bite, rather than a uniform, mince-like sauce.

Place a large sauté pan over medium-high heat. Add a little olive oil only if the sausage is lean. Add the sausage and spread it into the pan. Let it sear undisturbed for 2–3 minutes before breaking it up. Continue cooking until the sausage is browned, lightly crisp in places, and the fat has rendered into the pan. This stage makes or kills the dish. Pale steamed sausage is trash here. You need browned edges and rendered fat because that is the foundation of the sauce. Letting the sausage sit in genuine contact with the hot pan before disturbing it is what allows real browning to develop — sausage broken up and stirred from the moment it hits the pan releases moisture too quickly and simmers rather than searing, producing pale crumbles with none of the rendered fat this whole sauce depends on.

Lower the heat to medium. Add the finely diced shallots to the sausage and fat. Cook for 3–4 minutes until softened and translucent. Add the grated garlic and black pepper. Cook for 30–45 seconds until fragrant. If using white wine, pour it in and scrape the bottom of the pan. Simmer until mostly reduced. The shallots should soften into the fat, not brown aggressively. The garlic should smell sweet and fragrant, not burnt. Deglazing with white wine at this stage, scraping up the browned fond left behind by the sausage, carries that concentrated flavour directly into the sauce base rather than leaving it stuck to the pan.

Bring a large pot of salted water to a boil. Cook the pappardelle until just shy of al dente. Before draining, reserve at least 400ml of the pasta water. The pasta water is not optional. It carries starch, and that starch is what helps the sausage fat and Parmigiano turn into a sauce instead of greasy pasta with cheese clumps. Pulling the pasta while still just shy of al dente matters because it will continue cooking briefly once tossed into the hot pan with the sausage and pasta water — finishing it in the sauce rather than fully in the boiling water is what lets the noodles actively absorb some of that sauce rather than simply being coated by it afterward.

Transfer the pappardelle directly into the pan with the sausage. Add about 200ml reserved pasta water and toss over medium-low heat until the noodles start absorbing the sauce. Remove the pan from the heat. Add the finely grated Parmigiano-Reggiano gradually, tossing constantly. Add more pasta water as needed until the sauce turns creamy and glossy. Add the butter only if the sauce needs extra shine and body. Fold in the parsley off heat. The sauce should coat the pappardelle in a pale glossy layer and cling to the ribbons. It should not be watery at the bottom of the pan, and it should not split into oil and cheese. Add the Parmigiano off heat. If the pan is too hot, the cheese can seize and turn grainy. Removing the pan from direct heat before the cheese goes in protects the emulsion at its most vulnerable point — Parmigiano's proteins can seize and separate from their fat under too much direct heat, and tossing it in gradually while off the flame lets residual warmth melt it smoothly instead.

Taste and adjust with fine sea salt only if needed, since sausage and Parmigiano are already salty. Serve immediately in warm bowls with more finely grated Parmigiano-Reggiano, cracked black pepper, and a little extra parsley. The finished pasta should look creamy, pale, rich, and heavily coated, with browned sausage pieces visible throughout the wide ribbons.