Melt butter in 2-quart saucepan until sizzling; add onion and garlic. Cook over medium-high heat, stirring occasionally, until onion is softened (3 to 4 minutes).
Add tomatoes, tomato paste, 2 tablespoons basil and salt; continue cooking until mixture comes to a boil (1 to 2 minutes). Reduce heat to medium. Cook, stirring occasionally, until