1.Heat olive oil in a large stockpot over medium heat. Add the onion and shallots and cook until tender, about 10 mins.
Add the stock, broccoli, zucchini and dries thyme.
Bring to a boil, reduce heat to low and simmer for 15 mins or until vegetables are soft.
Stir in yogurt.
in 2-3 separate batches, purée the soup in a blender or food processor until smooth and creamy.
Return puréed soup to the pot and reheat.
To serve, ladle into warm bowls and top with basil and parmesan cheese, if desired,