Prepare the jars and lids, putting them in the pressure canner with a few inches of water. Place on low heat to heat the canner up ahead of time.
In a large stockpot, melt the butter and saute the onions and garlic for about 15 minutes.
Add the mushrooms and saute for another 5 to 10 minutes until the mushrooms are browned.
Add the wine, broth, and spices, bringing everything to a boil for five minutes.
Remove from the heat and ladle soup into hot jars. Ladle solids first, then divide the liquid evenly among them. Leave 1" of headspace.
Remove any air bubbles with a bubble removal tool, then ensure proper headspace. Add more broth or boiling water if needed.
Wipe the rims of the jars, then put the lids and bands on the jars. Tighten until they are fingertip tight, then load into the pressure canner.
Process the jars at 10 lbs of pressure for 45 minutes. You may need to adjust for altitude, see notes below.
Let the canner depressurize on its own after the canning time has elapsed. Remove the jars and let them cool for 12 hours.
Check the seals and store the jars for up to 12 months.
Enjoy!