I don’t have a recipe, but you really can’t make a mistake. Your soup will turn out great!
General: I freeze chicken carcasses, home roasted and rotisserie. Ok to smush them and keep adding to the same bag to save freezer space. The flavor comes from the bones, so no need to plop a whole chicken in a pot. All ingredients used to make the stock will be discarded so don’t waste the chicken meat. I do not roast the bones but go ahead if you want. I do save vegetable scraps in the freezer, but you don’t need to.
Stock: add chicken bones to a large stock pot. ( This was maybe 4-5 carcasses) Cover with water. I add any vegetable scraps from the freezer. If I don’t have a lot, I’ll add 1 or 2 quartered onions, 4 each carrot and celery stalks cut into pieces, corn cobs, parsley stems, whatever. I add bay leaves, whole peppercorns, whole allspice, sometimes whole garlic cloves. IMPORTANT-Add a healthy pour of vinegar. ( I used apple cider this time, but it doesn’t matter, the vinegar doesn’t add flavor but helps leach the minerals out of the bones and that’s your flavor.) Simmer the $hi+ out of this for many hours. The carcasses should be all falling apart, bones might even be disintegrating. Great! This simmered ~12 hours, I’ve done more and less. If you feel the need to add salt, use very little. I find it best to add at the table or the very end of cooking.
Remove large solids. Chill so fats will solidify on top and can be easily removed. Remove fats from top. Strain stock through a sieve to remove smaller solids. This can be used for soup or frozen for later use. It’s good if after chilling it is gelatinous. I do all this a day ahead.