Follow these step-by-step instructions to prepare a luscious Cream of Mushroom Soup that’s sure to impress:

1. Prepare the Mushrooms:
   • Clean the mushrooms with a damp cloth and slice them thinly. Ensure they are free from dirt and grit.
2. Sauté the Mushrooms:
   • In a large pot, melt 2 tablespoons of butter over medium heat. Add the mushrooms and cook until they are golden brown and have released their moisture, about 5-7 minutes.
   • Remove the mushrooms from the pot and set aside.
3. Cook the Aromatics:
   • In the same pot, add the remaining butter. Once melted, add the diced onion and sauté until translucent, about 3-4 minutes.
   • Stir in the minced garlic and cook for an additional minute.
4. Make the Roux:
   • Sprinkle the flour over the onion and garlic mixture. Stir continuously for about 2 minutes, ensuring the flour does not burn. This forms the base of the soup.
5. Add the Broth:
   • Gradually whisk in the chicken or vegetable broth, ensuring there are no lumps. Bring to a gentle simmer.
6. Blend the Soup:
   • Once the soup is simmering, use an immersion blender to puree the mixture until smooth. If you prefer a chunkier texture, blend only a portion of the soup.
7. Incorporate the Mushrooms:
   • Return the sautéed mushrooms to the pot. Stir in the heavy cream, thyme, salt, and black pepper. If using, add the white wine at this stage.
   • Simmer for an additional 10 minutes, allowing the flavors to meld.
8. Adjust Seasoning:
   • Taste the soup and adjust the seasoning with more salt and pepper, if necessary.
9. Finish and Serve:
   • Ladle the soup into bowls, garnish with freshly chopped parsley, and serve hot.