Melt the butter in a saucepan over medium-high heat. Add onion, carrot, and celery; sauté 4 minutes or until tender. Add broth, basil, pepper, and tomatoes, and bring to a boil. Reduce heat; simmer 15 minutes. Stir in 1/2 cup pasta. Remove from heat; let stand 5 minutes.
Place half of tomato mixture in a blender, and process until smooth. Pour puréed soup into a large bowl. Repeat procedure with remaining tomato mixture. Return puréed soup to pan; stir in remaining pasta and milk. Cook over medium-high heat 2 minutes or until thoroughly heated, stirring frequently (do not boil).