Alfredo sauce is still too bland... what am I missing?

I've made an alfredo sauce using this recipe, and twice it hasn't been quite right. 8oz cream cheese, 1 cup milk (we used 2%), 1/2 cup grated parmesean cheese, some nutmeg, some black pepper, and some garlic powder all melted on the stove top. The consistency was fine (almost like gravy consistency), but we agree that its...missing something.

I'm by no means a professional chef, (I have a 80% not-burnt-dinner rate.) so I thought this would be an easy way to change it up from jarred sauces... how can I fix this?

EDIT: Holy balls your responses. I'm really surprised that so many posts happened. I get it now, salt and butter and real cheese. Sorry if I sound completely ignorant, maybe I should have gone to a "cooking 101" thread first... Like I said though, I'm no chef. Thanks for everyone's input!