01 - Melt butter with olive oil in a large soup pot over medium heat. Add the chopped onion and sauté until translucent and softened, about 3 to 4 minutes.
02 - Add minced garlic and sliced mushrooms to the pot. Cook for 8 to 10 minutes, stirring occasionally, until the mushrooms are deeply browned and their released moisture has nearly evaporated.
03 - Stir in dried thyme, salt, and black pepper, coating the mushrooms evenly with the seasonings.
04 - Pour in the vegetable broth and bring to a boil. Reduce heat to low and let the soup simmer gently for 15 minutes to allow the flavors to meld.
05 - For a smoother, creamier texture, use an immersion blender to puree the soup directly in the pot to your preferred consistency. Skip this step if you prefer a chunky soup.
06 - Stir in the heavy cream and warm gently over low heat for 2 to 3 minutes. Do not boil. Taste and adjust salt and pepper as needed.
07 - Ladle the hot soup into serving bowls and garnish with freshly chopped parsley. Serve immediately with crusty bread or garlic toast alongside.