1 stick of butter (I use salted butter)
1 cup of Parmesan cheese (grated or shredded is fine)
1/4 tsp. garlic salt
1/8 tsp. ground pepper
pint of heavy cream
Melt butter. Add cheese and make a rue (it will still be separated). Add spices. Slowly add cream. Simmer for a few minutes. Add corn starch/water (or flour/water) mix if you want it to thicken up faster.
Here come the detailed instructions for you, Kates! ;)
I've never added the corn starch because I usually cook the noodles while the sauce is simmering so it has plenty of time to simmer and thicken. So really, I put the butter on to melt and then put the pasta water on to boil - then I continue making the sauce. By the time I've made the sauce and it's ready to simmer, the pasta water is boiling so I add the noodles. The noodles cook for 7-9 minutes, which means the sauce can simmer pretty low that whole time.
Oh and if you're going to make some broccoli to go with it, here's a trick to save you time. Just use a slotted spoon to scoop out the noodles (draining the water back in to the pot), and return the water to a boil. Throw the broccoli in there for a minute and drain. Voila!
And for some reason, we have never really liked homemade alfredo sauce with the typical fettucini noodles. It just doesn't work. I think the best way to serve it is over egg noodles. So yummy!