Saute onions in Olive Oil for a few minutes and then add in half of the fresh mushrooms. Stir until slightly soft. Add pepper, salt, garlic, thyme and 2-3 cups of beef broth. I used beef bullion cubes with 12 cups of water. Cook until mushrooms are getting soft. Puree cooked mushrooms until smooth like soup. Okay if there are some mushroom pieces still in the mix. Add in the rest of the broth, the spinach, mushrooms and stir. Cook another few minutes while you drain the Artichoke cans. Add in Artichokes (try not to stir too much so they will stay together more in the jars) and keep warm until canning.
Fill 7 quart jars with 1/2 inch head space. Process jars 50 minutes at 10 Lbs of pressure or your own location's pressure.
When serving the soup, stir in plenty of graded Parmesan and some pasta or small ravioli. Serve with hot bread or as a side.