Heat olive oil and butter in a non-stick pan. Add garlic and sauté for a minute. Add onions and sauté till they turn golden brown in colour.
Add tomatoes and cook further for three to four minutes. Add vegetable stock and bring it to a boil. Add salt, black pepper powder and sugar and mix well.
Lower the heat and cook till it reaches the soup consistency. Add half of the fresh basil leaves and mix well and cook for a minute.
Serve hot garnished with remaining basil leaves and Parmesan cheese.