Heat olive oil in large pot over medium heat. Sauté onion until translucent (5 min). Add garlic; cook 1 minute until fragrant.,Add tomatoes with their juices, stock, basil, sugar, salt and pepper. Bring to boil, then reduce heat and simmer uncovered for 25 minutes.,Remove from heat. Using immersion blender, puree soup until smooth (or blend in batches in regular blender).,Return to low heat. Stir in cream, butter and red pepper flakes. Heat through but don’t boil.,Adjust seasoning. Serve hot garnished with fresh basil, olive oil drizzle and Parmesan if desired.