Heat the olive oil in a large soup pot over medium heat, add the onion, and cook for 4–5 minutes until soft and translucent.
Stir in the garlic and thyme, cooking for another 30 seconds until fragrant but not browned.
Add the chopped zucchini and potatoes, stir to coat them with the oil and seasonings, then pour in the vegetable broth.
Bring the soup to a gentle boil, reduce the heat, and simmer uncovered for 18–20 minutes until the vegetables are completely tender.
Use an immersion blender to puree the soup directly in the pot until smooth, or carefully blend it in batches using a standard blender.
Return the soup to low heat, stir in the cream, and season gradually with salt and black pepper until the flavor is balanced.
Warm for another 2–3 minutes without boiling, then ladle into bowls and serve with herbs, cracked pepper, or crusty bread.