Clean vegetables and basil thoroughly. Remove coarse ends from zucchini and stems from basil and discard.
Chop zucchini, onion and garlic roughly, leave basil leaves whole
Add olive oil to a medium-to-large sized saucepan and place on cook-top at low to medium heat
Add chopped veggies to pan and saute lightly in oil for 1-2 minutes
Add 5 cups of prepared stock to the pan and stir (cold homemade stock is fine but stock made with bouillon stock powder and boiled water will help speed up the cooking process)
Add basil leaves to the pot, and stir.
Add salt and pepper and stir into the soup
Increase the heat until soup comes to a boil and then reduce heat to a simmer and put lid on saucepan (this reduces evaporation)
Cook soup for 20 minutes or until zucchini is just fork tender. (not mushy)
Remove soup from heat and blend with Bamix or regular stick blender directly in pot, blending until smooth. Alternatively, an upright blender may be used, just be sure to puree the soup in small batches to avoid risk of scalds!
When soup is smooth add 1/4 cup heavy whipping cream and use Bamix, regular stick blender or upright blender to mix thoroughly.
Taste a little of the soup and adjust seasoning if needed.
To serve, ladle into individual bowls/ramekins, swirl in 1 tsp of cream per bowl and sprinkle with finely chopped basil.