1. Preheat oven to 450°. Toss together first 7 ingredients and 1 tsp. salt. Arrange in a single layer in a 15- x 10-inch jelly-roll pan.
2. Bake at 450° for 30 to 35 minutes or until vegetables are tender and lightly browned, stirring halfway through. Remove from oven; process 2 cups squash mixture and 1 cup broth in a blender or food processor until smooth. Divide remaining squash mixture among 4 shallow soup bowls.
3. Stir together vegetable puree and remaining 2 cups broth in a 3-qt. saucepan; bring to a boil over medium heat, stirring occasionally. Remove from heat; whisk in butter, lime juice, and remaining 1/2 tsp. salt.
4. Spoon broth mixture over squash mixture in bowls. Sprinkle with fresh herbs, and serve immediately.