I call this white sauce and not Alfredo, because you will see that my sauce is different from Alfredo (which is usually just cream and butter). Mom always made a besciamella sauce, and I do too! She used this for fettucine Alfredo and as the cheese sauce in her lasagna. I will describe how to make it now.
4 tablespoons butter (I usually use salted)
4 tablespoons flour
1 qt half and half
1 tsp salt
fresh nutmeg (please buy the whole seed and grind it as needed on a rasp)
Start by making a roux. That is a fancy French way of saying brown your flour with your butter in a low heat pan! Actually, there is some technique involved. Start by adding your butter to a low heat pan. Let it melt and start to boil just a bit to get the water boiled off. Then add the flour (I actually add just a touch more butter than flour because some of the butter DOES boil off) to the butter and begin to stir with a wire whisk.
Keep it over low heat and keep whisking it. At first it will be very tight and clumped together. Keep going ( use those elbows). Soon it will start to loosen a bit. About the time it starts to loosen, you will smell it start to toast. You will also see it change color to a light blonde from pasty white.
Now, take it off the heat and while whisking slowly, start adding the half and half a little at a time. Take it SLOW! Add a small amount, then stir it vigorously between additions! ADD ONLY SMALL AMOUNTS of LIQUID! If you do this, you will see it get very thick as the starches in the flour bind with the liquid, then as you continue to stir and add, it will start to smooth out. Finally, when all is added, it will be incorporated and lump-free!
Now add your salt and about six or eight passes of nutmeg over the grater. Just enough to give it some flavor. Slowly bring it to a boil, stirring it often. It will begin to thicken nicely at this point.
You now have a very nice besciamella sauce. It is ready to be flavored.
Slowly add 1/2 cup of grated Parmesan or Romano (for a nice Alfredo)
Add about two cups of ricotta (for a cheese sauce for lasagna)
You can add garlic and fresh herbs as you like to increase flavor for your preference. Lots of time I add three cloves of roasted garlic and Romano cheese for a really nice Alfredo. I top it off with a little fresh flat-leafed parsley for some color. I hate to admit it, but I can and do substitute skim milk a lot of times to save some fat and calories. It is good enough that way for an every day sauce. Ramp it up to whole milke or 1/2 and 1/2 for the special occasions.