Boil a salted pot of water and cook your pasta al dente according to package directions.
Meanwhile, fry the sausage in a skillet until browned over medium-high heat, breaking it up as you go along (about 7-8 minutes). When it's done, transfer it to a paper towel lined plate. If there's a lot of excess fat in the pan, drain it.
Add the butter to the skillet and let it melt, then add in the mushrooms. Cook them, stirring occasionally, for about 5-6 minutes or until they release water and it's been cooked off.
Stir in the garlic and cook for 30 seconds.
Take the mushrooms out of the pan (add them to the same plate that has the sausage).
Add the wine, oregano, lemon juice, and flour to the skillet. Give it a good stir (only let it cook for about 1 minute).
Stir in the cream, and then add the mushrooms and sausage back to the skillet. Let it warm through/cook for a few more minutes until it's slightly thickened, then drain the pasta and add it to the skillet and toss. If the sauce thickens up too much, add in a splash of the hot pasta water prior to draining it. Season with salt & pepper if needed (taste first as the sausage can be quite salty!) and serve with parmesan cheese and parsley if desired.