Unfortunately the "cream" in that soup is not safely canable and as a result it has been overlooked as a great soup in the pantry. I say "nay nay" to that since the earthy taste of mushrooms with a beef or chicken broth base has amazing flavor and will line my pantry. I have come up with a safe way to can this soup that I think taste a million times better than its commercial rival. It's easy to make and takes no time from pulling it from the canning pantry to making it creamy on the stove.
There are two methods to adding the "creamy". One is a roux method and the other is using heavy cream. Either way you will taste the mushrooms, spices, and broth more intensely than the Campbell version.
Canning Mushroom Soup Base
Makes 10 cups (5 pints)
2 lbs mushrooms, stalks removed (Buy 2 1/2 lbs)
6 cloves garlic
1 1/2 t. dried thyme
8 cups veggie, beef or chicken stock/broth
1/4 t. nutmeg (optional)
Preparation : Prepare 5 pints, lids, and rings. Sterilize the jars and keep them in the hot water till its time for processing. Make sure to fill your pressure canner with the recommended amount of water and bring it to a simmer. Slice mushrooms, not too thin, as they will cook down in the pressure canner. Mince the garlic and set them both aside.
Cooking: In a large stainless steel heat beef broth/stock over medium heat. Remove from heat.
Filling the jars: On a dishtowel place your hot jars and using your funnel in each jar fill the jars with mushrooms to 3/4 full. Add 1 teaspoon of garlic, 1/2 t. dried thyme and a pinch of nutmeg (optional). Once all the jars are filled add hot stock leaving 1” headspace. Remove air bubbles and refill to the proper headspace if necessary. Taking a clean papertowel wet it with vinegar and wipe the rims of the jars removing any food particles that would interfere with a good seal. Using your magic wand extract the lids from the hot water and place them on the now cleaned rims. Add your rings to the tops of each of the jars and turn to seal just "finger tight".
Processing: Make sure your rack is on the bottom of the canner and place the jars in the pressure canner. Lock the lid and turn up the heat bring the canner to a boil. Vent steam for 10 minutes, then close the vent by adding the weighted gauge or pressure regulator (for dial gauge canner). Process pints for 75 minutes at 10 lbs of pressure (11 lbs for dial gauge canner) and quarts at 90 minutes. (Adjust pressure for altitude) When complete turn off the heat and let pressure return to zero naturally. Wait two minutes longer and open vent. Remove canner lid. Wait 10 minutes then remove jars and place on dishtowel in a place that they will sit overnight to cool. Do not touch or move them till the next morning.
Sealing: Some time in the next hour your jars will be making a "pinging" or "popping" noise. That is the glass cooling and the reaction of the lids being sucked into the jar for proper sealing. Some recipes may take overnight to seal. Check your lids and reprocess any jars that did not seal. Remove rings for storage.
For making the soup creamy when serving: for pint size. Double for quarts.
In a sauce pan add 1 T. of butter and 1/8 cup of flour. Stir over medium heat till the rouge is heated. Add a bit of the liquid from the jar and heat till simmering hard, whisking so you have no lumps. Add the remaining liquid and contents of the jar and heat till you achieve the thickness desired. To use cream to thicken start with 1/4 cup and stir till hot. Add an additional 1/4 if you like it thicker.