Bring a large pan of salted water to the boil. Cook the pasta according to pack instructions.
Two minutes before the pasta is done, scoop out 100ml of the cooking water and set aside.
Drain the pasta and return it to the warm pan.
Add the butter, cream cheese, garlic and mixed herbs to the pasta.
Pour in a splash of the reserved pasta water and stir vigorously until the cream cheese melts into a smooth sauce. Add more water if needed.
Stir in the salt, pepper and parmesan if using.
Serve immediately while hot and creamy.