In a large pot or Dutch oven, heat the olive oil over medium heat. Add the diced onion and sauté for 2-3 minutes until translucent.
Stir in the minced garlic and cook for another minute until fragrant.
Add the diced carrots, celery, and potatoes to the pot. Sauté for about 5 minutes, stirring occasionally.
Pour in the vegetable broth and add the corn, green beans, dried thyme, and dried basil. Bring the mixture to a boil, then reduce the heat and simmer for 10-15 minutes, or until the vegetables are tender.
Once the vegetables are cooked, use an immersion blender to blend the soup until smooth, or allow it to cool slightly and blend in batches in a regular blender.
Return the blended soup to the pot (if using a regular blender) and stir in the heavy cream. Heat the soup over low heat until warmed through, about 5 minutes.
Season with salt and pepper to taste.
Serve hot, garnished with chopped fresh parsley if desired.