Bring a pot of well salted water to the boil and cook the pasta, reserving a cup of pasta water before draining. I tend to undercook dried pasta by a minute so it can finish cooking in the sauce.
Squeeze the sausage meat out of the casings. I like to roll it into tiny meatballs but you can also break it up in the pan for more of a ground meat texture.
Heat a large skillet over medium-high heat and add the olive oil and butter. Toss the mushrooms in then leave pretty undisturbed for 5-7 minutes, turning once until golden. Set aside on a plate.
Add a drizzle of olive oil to the pan then add the sausage meat and cook for 3-4 minutes until golden.
Turn the heat down to medium and add the garlic and thyme, cooking for 30 seconds until fragrant.
Pour in the wine and simmer for 3-4 minutes until slightly reduced, scraping up any browned bits from the bottom of the pan for extra flavor.
Add the mushrooms back into the pan with the cream, bringing to a very gentle simmer.
Push the sausage and mushrooms to one side of the pan then add the Parmesan cheese in three separate lots, letting each addition melt before adding the next. Keep the heat low and stir continuously so the cheese melts gently into the sauce.
Add the cooked pasta with a small splash of pasta water (a bit less than ¼ cup), the black pepper and lemon juice and toss well. Let it gently bubble away for 2-3 minutes over a low heat to thicken. It will look loose in the pan but creamy sauces dry up a lot off the heat.
Taste and adjust seasoning with salt if needed.
Toss the parsley through right before serving and finish with lemon zest, extra parmesan and extra cracked black pepper if you like.