I think my cooking changed big time when I learned the importance of rich stock in the kitchen. It is both flavorful and nutritious.
Chef Parker Bosley first taught me about stock. He is very particular about it and can wax on poetically about the nuances he has picked up over the years.
I'll try to make it very simple.
Don't even put your chicken backs in the freezer. Put them in a stockpot right away. If you aren't going to make stock tonight, put them in the stockpot in the fridge to thaw so you don't forget about them.
Repeat. The freezer is where food goes to die slowly. Just start cooking it now.
Add to the stockpot (optional) a few branches of celery (or frozen celery leaves from the summer), a few peeled carrots, an onion, a few cloves of garlic, and (if you have it) a few sprigs of fresh thyme or about a teaspoon of dried thyme.
Fill the stockpot with cold water until the bones are submerged by about an inch or more.
Bring the water to a simmer - just barely a boil - and let it simmer for at least 4 hours. I often find the perfect setting and let it roll overnight (be careful not to evaporate the water and scorch your pan).
Strain out the bones and solids while the stock is hot. Pass it first through a colander to remove the large pieces, then a second time through a fine sieve (like a chinois) or a damp kitchen towel. Refrigerate overnight.
The fat will solidify on the top after it is cold. Remove the fat. If the stock is not "rich" enough for you, simply reduce it down at a boil. Some like lighter stock that is more of a broth, while other applications call for a rich stock that is thick in gelatin.
That's all there is to it. If you don't want to do it on the stovetop, you can also do the same thing in a crock pot. The fastest way to make stock is with a pressure cooker or Instapot - same process, just less time.
I made the stock, now what do I do with it?
You've probably heard all the buzz around bone broth, right? Same thing. Drink it for it's health benefits. If you do drink it, don't forget to season it some with salt and pepper.
Stock is also an important component of cooking. Use it to braise a pork roast or as the base for a soup. It also can be used to make gravy or to add flavor to a ragout of asparagus and ramps or even a risotto. The applications of stock are endless. It has become one of the "staples" in my refrigerator that is in my toolbox for any meal that might arise.