Heat a large frying pan over medium-low heat and add the oil and minced garlic to the warm pan. Saute the garlic until soft and fragrant, about 3 minutes. Boil salted water for pasta.
Add the sliced mushrooms to the pan. Saute until the mushrooms begin to brown, about 5 minutes. Add 1 tsp of salt to the mushrooms and saute for another minute.
At this point add the pasta to the boiling water to cook.
Add the butter to the pan with the mushrooms and saute until it melts. Once the butter melts pour in the heavy cream and let it simmer with the mushrooms for 4 minutes. Slowly mixing in the parmesan cheese and continuously stir until the cheese melts and mixes in.
Reserve 1/4 cup of the pasta water and drain the cooked pasta. Mix the pasta water and cooked pasta in with the sauce. Toss to combine and cook for another 2 minutes. Serve with fresh basil, parmesan cheese and truffle oil
Notes
Save some pasta water before draining. The starchy water is great for loosening up the sauce if it gets too thick. Add it a splash at a time and stir until the sauce reaches the right consistency.
Do not let the sauce boil. Once the cream is added, keep the heat at a gentle simmer. A hard boil can cause the sauce to break and turn greasy.
Use freshly grated parmesan. Pre-shredded parmesan has added coatings that stop it from melting smoothly. Freshly grated parmesan melts much better and gives a creamier sauce.
Add the pasta straight to the sauce. Instead of draining the pasta and then adding sauce, transfer the cooked pasta directly into the pan and toss everything together. This helps the sauce coat every piece of pasta evenly.