Cook spaghetti in salted boiling water until al dente
Drain the spaghetti and set aside
Blend cilantro, parsley, poblano or jalapeño, garlic, onion, sour cream or crema, milk, and a little salt
Heat butter or oil in a pan
Pour the green sauce into the pan and cook over low heat
Stir in cream cheese or more sour cream if desired
Add cooked spaghetti to the sauce
Toss until evenly coated
Adjust salt to taste
Serve warm with cheese on top if desired