We make "white sauces" quite a lot and sometimes don't even realize that this is what we're doing.
Ever made gravy? That's a browned white sauce. Ever thickened soup with flour? Make cheese sauce? Same principle.
Sauces in general are nothing more than a fluid that has been thickened and has had some spices, for flavor. Then you can brown it or not. You can add other ingredients such as eggs, cheese, mushrooms, or other herbs.
Before I make my sauce/gravy I make sure I have what I need on hand. Yeah, ok, so that's a no brainer. But is your cheese already grated, measured out and ready to be dumped into the sauce? Are the mushrooms cleaned, sliced or chopped, cooked, measured and ready to be dumped? Are your seasonings out, lids off and ready to go? Gottcha. Once the sauce is ready to have the add-ins added in, you don't want to have to leave it to go do these things. You risk the sauce scorching on the bottom. You want to be able to stir with one hand while adding stuff with the other. That way it won't scorch and you won't get popped with hot gravy - and it DOES pop when it cooks - unless you keep stirring it, and even then sometimes you get popped.
Traditional basic sauce: (can be doubled, tripled or more)
2 Tbs Fat source - butter, margarine, rendered fat(chicken, beef, bacon, etc) or oil
2 Tbs thickener - flour, cornstarch, tapioca, arrowroot, bean flour, etc
1 cup liquid - milk, cream, water, stock, broth, liquid from drained veggies, pan drippings or a combo of these
This is made into a medium thick sauce by melting/warming the fat source over a medium low heat. If you want the sauce to stay white, you need to use milk and not let the fat brown. When the fat is melted/warmed, add the thickener to it and stir it around. The best thing to use is a wire whisk, but in the days before I owned a whisk, I used a spoon or fork.
Remove the pan from the heat and slowly add in the liquid, stirring in a bit of liquid at a time and thoroughly incorporating it into the flour before adding more. This takes a bit of patience, but it will keep lumps from forming. You want a smooth mixture.
After the liquid is completely mixed in, return the pan to the heat and keep stirring it. Truthfully, I turn the heat up to med-high and stir it constantly. It will thicken as it comes to a simmer. Turn the heat down and keep stirring it. Let it cook for about 3 minutes. You may want to keep the heat down so you don't scorch it, especially if you're using milk or cream.
Now you need to make some decisions. If you want to freeze it, this is the point to do so. Freezing changes the flavors of sauces, killing some of the taste. It's best to freeze it and then add the seasoning to it when you're ready to use it. You can divide the sauce up into portion size servings or put it into ice trays and then, when it's frozen, pop those into a zip bag. Oh, and don't freeze this if you've used cream for the liquid. If you do, the sauce breaks down upon thawing.
Season your sauce with whatever rings your chimes. Around here it's Adobo (without pepper), some salt, garlic powder, and onion powder. (Part of me will be glad when I'm only cooking for me again and can use the "real" stuff. Kids, gotta love 'em but I'm sure gonna miss 'em.) Here is where you'd add any special ingredients you'd like to use - herbs, mushrooms, cheeses, etc.
Variations:
Thinner sauce:
1 Tbs fat
1 Tbs thickener
1 to 1 1/2 cups liquid
Thicker sauce:
4 Tbs fat
4 Tbs thickener
1 cup liquid
Cheese sauce:
Add 1/2 to 3/4 cup shredded cheese, tightly packed, for each cup of sauce. That's about 1/8 to 1/4 pound of cheese. If it's too thick, thin with milk.
Mushrooms:
1 cup mushrooms, sliced or chopped to each cup of sauce
Cook in butter, bacon grease or olive oil and add to the white sauce.
To make cream of mushroom soup, use a thin white sauce and the mushrooms.
Bechamel sauce:
Reduce the flour to 1 1/2 Tbs. After making the sauce, beat either on egg or just the yolk of an egg to a froth. Stir in a 2 tbs of the hot mixture into the egg and mix that well, add another 2 Tbs and mix that well (temper the egg) and then add the egg mixture into the sauce and stir well. This will not freeze well either.
Alfredo sauce:
1/2 cup Parmesan cheese, grated, per cup of sauce
1 Tsp garlic or garlic powder (opt)
Yep, that's all it is! Too easy for something so expensive.
Now in a total departure from "rules", this is how I make gravy. When I cook my meat, there is usually some "drippings" left in the pan. If you fry meat, stuff sticks to the bottom of the pan. Unless you've cooked the meat in a LOT of fat, you don't need to strain off the fat. We tend to not use much fat when frying. I use cast iron pans and we keep them well seasoned so that only a Tbs or so of fat is used. When the meat is done, I will add water to the pan and "deglaze" it - stirring the water around until it picks up the bits of meat and the "fried on" stuff. It adds flavor to the water and you get "free" gravy. I then use this water to make the gravy. If I want more meat flavor, I sometimes will add a bouillon or two to the water.
When I make a roast, I use the pan drippings, add water and deglaze the pan just like I would with fried meat (if anything has stuck to the bottom of the pan). When I make a turkey, I will simmer the neck, gizzard, and the heart with an onion, rib of celery, some poultry seasoning, salt and I use a 3qt pot. I add water to cover the ingredients, refilling as needed. Bring to a boil, then lower to simmer, cover and let it cook while the turkey cooks. When the turkey is done, I strain out the veggies and add this to the pan drippings to make my gravy. (I remove the giblets, but you can dice them and add them back to the gravy. Again, kids) I don't use the liver in the pot as it's too strong. I cook it with the meat and either eat it or give it to the dog.
Measure out how much liquid you want to end up with. If you want 3 cups of gravy, then you need to start with 3 cups of liquid. (I know: well duhhhh)
2 cups of that liquid will go into a pan, turn the heat to med and start warming it up. Take the remaining 1 cup of liquid and add it SLOWLY, to 1/2 cup thickener (we like thick gravy), stirring after each addition, so that it makes a smooth paste. Then add just a little more liquid to it so that it will pour - you want a slurry(we're not making dumplings, lol). Slowly add the flour mixture into the pot with the warm liquid in it, stirring constantly. Bring it to a slow boil and KEEP stirring it. Let it cook for about 3 minutes on low while you add the seasonings to it. Keep stirring it frequently while you do this! Again, our personal cast of reoccurring characters are Adobo, onion and garlic powder and salt. Though I do use sage, thyme and other herbs depending on what meat I've used. I will sometimes add a tbs of bacon grease to the pot too.
Notice that I make the gravy without added fat. You don't HAVE to have fat to make gravy, any more than you HAVE to use flour to make it.
What you DON'T want to do is to try and add the thickener TO the liquid. Always add liquid to the thickener. Add a bit and stir it up, then add a little more liquid and stir that up, until you have a slurry. A slurry is thinner than a paste. This is the secret to lump-free gravy.
Oh, and if like me you fail to measure your liquid, you just eyeball it and then it turns out too thin; just add some more thickener to a cup, bowl, measuring cup, whatever will hold liquid/thickener and add enough liquid to make a slurry - just like we did before. (Great run on sentence!) If your slurry doesn't have lumps, your gravy won't have lumps, so make sure the slurry is smooth.
Ok, so now it's TOO thick - add more of your liquid to thin it out. But JUST a LITTLE at a time and stir it well!
For those that need gluten-free sauces or gravy, select the gluten-free thickeners. I believe that the list would include the cornstarch, rice starch, arrowroot, bean flour, and tapioca. Since no one I personally know needs gluten-free, I'm not positive about this list. As always, read the label on the package. Also, there may be more choices, but I don't know them.