Heat olive oil and butter in a large pot over medium heat. Add the onions and garlic, sauté until softened.
Add sliced mushrooms and cook until tender, about 5-7 minutes.
Pour in the vegetable broth and bring to a simmer. Let it cook for 10 minutes.
Stir in cream cheese and heavy cream, and cook until the cream cheese melts smoothly into the soup.
Season with salt and pepper to taste.
Optional: Use an immersion blender to partially blend the soup for a smoother texture.
Garnish with fresh thyme or parsley before serving.