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.