Cook the spaghetti by boiling 8 cups of water with a table spoon of olive oil and a pinch of salt, add spaghetti to the boiling water then simmer gently for 6-8 minutes or until cooked through. Immediately, drain it.
For the sauce, heat olive oil in large nonstick skillet over medium heat. Add onion and garlic; cook 4 minutes, add the mushrooms and stir until the mushrooms are cooked.
Add the butter, cream, salt, pepper and basil, stir and cook for 3 more minutes.
Mix the sauce with the spaghetti .Serve hot with grated parmesan cheese on top .