Heat olive oil in a large pot over medium heat. Add onions and garlic, cooking until softened, about 3-4 minutes.
Add the sliced mushrooms and cook for 7-10 minutes until browned.
Pour in the white wine and cook for another 3-5 minutes until it reduces slightly.
Add vegetable broth and bring to a simmer. Cook for 15 minutes, allowing the flavors to meld together.
Stir in the heavy cream, thyme, rosemary, salt, and pepper. Simmer for another 5 minutes.
Puree the soup with an immersion blender until smooth (optional for a creamy texture).
Taste and adjust seasoning as needed. Garnish with fresh parsley before serving.