In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for about 5 minutes until softened.

Stir in the minced garlic and cook for an additional minute until fragrant.

Add the chopped celery and diced potatoes to the pot. Stir to combine and cook for about 5 minutes.

Pour in the vegetable broth, then add the dried thyme, salt, and black pepper. Bring the mixture to a boil, then reduce the heat and let it simmer for 20-25 minutes, or until the potatoes and celery are tender.

Using an immersion blender, puree the soup until smooth. Alternatively, you can carefully transfer the soup in batches to a blender.

Return the pureed soup to the pot and stir in the heavy cream. Heat through for another 5 minutes, then taste and adjust seasoning if necessary.

Serve hot, garnished with fresh parsley.