Heat olive oil in a large pot over medium heat. Add chopped onion and sauté until translucent.

Stir in minced garlic and sliced mushrooms; cook until mushrooms are tender and browned.

Pour in vegetable broth, thyme, salt, and pepper. Bring to a boil, then reduce heat and simmer for 15 minutes.

Using a blender, carefully blend the soup until smooth.

Return the blended soup to the pot, stir in heavy cream, and simmer for an additional 5 minutes.

Serve hot, garnished with chopped parsley.