In a large pot over medium heat, melt the butter and bacon drippings. Add diced onions and sauté until they become translucent and slightly caramelized, about 5 minutes. Add minced garlic and sauté for an additional 30 seconds until fragrant.
Add the sliced brown mushrooms to the pot. Cook and stir occasionally until the mushrooms release their moisture and start to brown, about 8-10 minutes.
Sprinkle the flour over the mushroom mixture and stir well to coat the mushrooms evenly. Cook for 2-3 minutes to cook off the raw flour taste.
Pour in the red cooking wine to deglaze the pot, scraping up any flavorful bits from the bottom. Let the wine simmer for a couple of minutes to reduce slightly.
Pour in the chicken stock and dissolved beef bouillon cubes. Stir in dried thyme, season salt, and black pepper. Give it a good mix and let the soup come to a gentle simmer.
Allow the soup to simmer uncovered for about 15-20 minutes, letting the flavors meld and the soup slightly reduce.
Reduce the heat to low and stir in the half and half. Let the soup heat through without boiling.
Now it's time to turn it into that condensed goodness! Simmer the soup on low heat, stirring occasionally, until it thickens and reduces by about half. This is where the magic happens – the flavors intensify, and your soup becomes concentrated.
Taste the condensed soup and adjust seasonings as needed. Add more salt, pepper, or thyme according to your preference.
Allow the condensed soup to cool slightly before transferring it to pint-sized jars. Seal the jars tightly and store them in the refrigerator for a few days or freeze them for longer storage.
Voilà! You've just created a batch of homemade savory condensed cream of mushroom soup. This versatile base is your secret weapon for elevating dishes with that irresistible mushroom richness. Enjoy!