Cook pasta in salted water according to package instructions.
In a large skillet over medium high heat, sauté onions in olive oil until they start to become translucent. Add in the butter, garlic, and mushrooms and cook for about 4 - 5 minutes.
Add in a splash of white wine and mix. Season with salt, pepper, and Italian seasoning.
Add in the cream, black truffle sauce, and the pasta water. Stir throughly.
Reduce heat to low and add in the cheese and pasta. Toss everything to combine.
Serve with more grated parmigiano reggiano, fresh chopped parsley, and a light drizzle of truffle oil. Enjoy!