What can I substitute for butter in Alfredo sauce? While I was cooking a very simple Alfredo sauce today for my lunch, I had already started my sauce before I realized I was out of butter. 

If this happens again to me in the future, what is a good emergency replacement for butter in a recipe? 

My recipe (if needed) was:


  
  1 1/2 cups butter, divided 1 pound skinless, boneless chicken breast
  halves - cut into cubes 
  2 (16 ounce) containers whole milk ricotta
  cheese 
  1 pint heavy cream 
  1 teaspoon salt 
  1 cup grated Parmesan cheese
  
  
  Bring a large pot of lightly salted water to a boil. Add fettuccini
  and cook for 8 to 10 minutes or until al dente; drain.
  
  Melt 2 tablespoons butter in a large skillet over medium heat. Saute
  chicken until no longer pink and juices run clear.
  
  In a large saucepan combine ricotta cheese, cream, salt, Parmesan
  cheese and remaining butter. Cook over medium heat until well
  combined, about 10 minutes. Stir in cooked fettuccini and chicken;
  cook until heated through.


What I ended up doing was adding some EVOO to the sauce because I figured it had a similar fat content. The sauce turned out ok enough, but I'm wondering what the difference would have been if I had used actual butter.
This is 100% about flavor. Butter will give you this, EVOO will give you that, ...

Butter will give you a 'richer' taste, whatever that may mean for you.
Extra Virgin Olive Oil, generally speaking is far more powerful and may become overwhelming.
Any other oil will give you a different taste profile. 

Sunflower oil may be the most neutral and therefor the most appropriate for Alfredo sauce. Cannola oil may be another neutral oil, but I've never used it myself.

Generally speaking, an oil is an oil is a fat (for emulsifying).