Add the olive oil to a pot along with the chopped onion, crushed garlic, dried basil, dried thyme and dried rosemary and sauté until the onions are softened.
Add the sliced zucchini and toss it with the onions and spices.
Add the vegetable stock and bring to a simmer.
Cover the pot and let it simmer until the zucchini is soft and cooked.
Turn off the heat and blend the soup directly in the pot using an immersion blender. If you don't have an immersion blender then allow the soup to cool for a bit before transferring it in stages to your blender jug. Blend it and then return all the blended soup to the pot.
Add the heavy cream and stir it into the soup.
Add salt and pepper to taste.
Ladle into bowls and serve topped with freshly grated parmesan, a sprinkle of ground black pepper and some fresh thyme.