1In 3-quart saucepan, melt butter over medium heat. Add onion and garlic; cook 2 to 3 minutes, stirring constantly, until onion is crisp-tender.
2Stir in tomatoes, broth, 1 tablespoon of the basil, the sugar and pepper flakes. Heat to boiling. Reduce heat; cover and simmer 15 minutes. Remove from heat; pour mixture into large heatproof bowl; cool slightly, about 15 minutes.
3In blender, place half of the mixture. Cover; blend until pureed. Return to saucepan. Repeat with remaining mixture. Heat over medium heat until hot. Remove from heat. Stir in cream and remaining 1 tablespoon basil.