I tried this recipe and it was simple and tasted pretty good.
http://www.foodnetwork.com/food/recipes/recipe/0,1977,FOOD_9936_26988,00.html
But I like to make big batches of Alfredo sauce so I normally use a different recipe.
1/4 pound unsalted butter
6 oz of flour
1/3 teaspoon salt
2/3 tablespoon white pepper
This is for the Rue. Cook for 5 minutes until it has applesauce like consistency. Let it cool down and put it in the fridge.
In a pot, heat 2 quarts of half & half cream and 1 quart of heavy cream to a froth and then add the cooled rue. Wisk briskly for 5 minutes and then strain through china cap.
This makes a big batch good for countless Fettuccine Alfredo. I add chopped garlic, more salt, and fresh and grated parmesan cheese later as I'm cooking individual portions in the skillet. You can add fresh vegetables and grilled chicken later as well. You can freeze the alfredo sauce to keep for around 3 months.