Take all the meat off the carcass and set it aside.
Break the carcass up into pieces that will fit into your stockpot. Include all bones, bits of fat, trimmings, etc., but do not include the liver if you have it. You don’t mention stuffing the bird, and this is good. Because if you HAD stuffed it, you ought to wash all remains of the stuffing out of the carcass. It will make your soup taste weird, if you leave it in.
Cover with cold water. The cold liquid may include a box or can of chicken stock if you like, or a Knorr Swiss chicken cube may be put in. Bring quickly to a boil and skim off the worst of the glop that rises to the top.
Peel and chop fairly small: 2 large carrots, 2 onions. Chop 2 sticks of celery. Drop these vegetables into the pot.
Add 1 bay leaf, a good pinch of leaf thyme, another goodish pinch of leaf rosemary, maybe a dozen whole black peppercorns, and a half teaspoon of red pepper flakes. If you have some parsley, chop it up and drop in a couple of tablespoons of it, or some dried parsley. Not necessary, but nice.
If you have any lemons, cut a lemon in half and put it in, peel and all, after giving it a bit of a wash. You may also add 2 whole cloves, but if you don’t have these things, it’s okay.
When it comes back up to the boil, reduce the heat to simmer and cover the pot. Simmer for no more than 2 hours. Any longer and it starts tasting only of bones.
Strain the stock, pressing hard on the solids, and discard everything but the actual liquid. Put it in the fridge overnight, and in the morning lift off the fat that has congealed on top. You may, if you wish, pour it carefully into another container in such a way as not to disturb the stuff at the bottom. But if you don’t, that doesn’t matter at all.
At this point, you may freeze your stock. And with it, but in a separate container, freeze the meat you intend to put in your soup when you eventually make it.
However, if you are going to make your soup now, put it on the stove again and add a couple of carrots sliced thin or chopped, a stick or two of celery sliced thin, a bit more thyme and rosemary if desired.
I like to put in a can of Green Giants Niblets corn, or some frozen corn kernels.
If you are intent on adding garlic, at this point drop in a couple of whole peeled cloves.
You may add a couple of potatoes cut up small, or a half a cup of rice, or some noodles. Or all of them.
When the potatoes/rice/noodles are done, put in the nicely chopped turkey meat you have saved. You don’t need a lot of it.
Don’t boil the soup hard, let it simmer, should have the vegetables done in a half hour.
Taste your soup. Add salt and pepper to taste. Enjoy.
ps: you may find that your stock isn’t flavoured strongly enough for you. You can add some more chicken stock, or a Knorr Swiss cube if you like.