In a large pot, heat the olive oil over medium heat.
Add the onion and garlic to the pot and sauté until softened.
Add the mushrooms to the pot and cook until browned.
Pour in the vegetable broth and bring to a boil.
Reduce the heat and simmer for 20 minutes.
Using an immersion blender or regular blender, puree the soup until smooth.
Return the soup to the pot and stir in the heavy cream. Season with salt and pepper to taste.
Simmer for an additional 5 minutes.
Serve the soup hot, garnished with fresh parsley.