In a large dutch oven, melt the butter over medium-high heat.
Add onion and cook for about 4 minutes, then add garlic, keep stirring for 1 minute or until the onion is tender.
Add dried basil, salt, and pepper. Stir for about 30 seconds.
Add zucchini, broth, and water into the pot. Bring to a boil.
Once boiled, reduce the heat to medium-low heat, bring the soup to simmer, covered for about 15 minutes or until the zucchini is soft.
Turn off the heat and let the soup cool slightly.
Use a hand blender to puree the zucchini soup until smooth.
Turn the heat back on and add heavy cream. Keep stirring until well combined.
Turn off the heat and serve the soup warm. Enjoy!