Heat olive oil and butter in a large pot over medium heat until the butter foams, roughly 1 minute. Add diced onion and cook until translucent and soft, stirring occasionally for 4-5 minutes, then add minced garlic and cook another minute until fragrant.

Add chopped zucchini to the pot and stir to coat with oil, then pour in vegetable broth and bring to a gentle boil. Reduce heat to medium and simmer for 15 minutes until zucchini pieces are completely tender and fall apart when pressed with a spoon.

Season with dried basil, oregano, salt, and black pepper according to taste preference. Stir well and let flavors meld for approximately 2 minutes before proceeding to the blending stage.

Working carefully with hot liquid, use an immersion blender to puree the soup directly in the pot until completely smooth. Alternatively, transfer soup in batches to a standard blender and puree until silky, then return to the pot—the summer zucchini soup family recipe comes out equally smooth either way.

Reduce heat to low and stir in heavy cream, fresh parsley, and grated Parmesan cheese, stirring constantly for 2-3 minutes until everything is well combined. Squeeze fresh lemon juice throughout the soup for brightness and taste once more for salt and pepper adjustments.

Ladle into bowls and garnish with additional Parmesan, fresh basil leaves, or a drizzle of quality olive oil. Serve immediately while steam rises from each bowl for maximum comfort and satisfaction.