Preheat oven to 425 degrees F. Place butter in a 15x10x1-inch baking pan. Heat pan with butter in the oven for 1 to 2 minutes or until butter is melted; swirl butter in pan to coat the bottom; set aside.
Halve squash, cutting from blossom to stem end. Remove seeds and discard. Cut squash crosswise into 1-inch slices, discarding stem end. Place squash in a single layer in prepared pan. Drizzle with olive oil and sprinkle with salt. Turn each squash slice to coat with oil or butter.
Roast, uncovered, about 45 minutes or until squash is tender and browned, turning squash slices once or twice. Transfer to a serving platter. Spoon Reduced Balsamic Drizzle over squash. Makes 8 servings.
Reduced Balsamic Drizzle
In a small saucepan, combine balsamic vinegar, honey, bay leaf, and rosemary. Bring to boiling. Boil gently, uncovered, about 30 minutes or until mixture reduces to 1/3 cup. Remove bay leaf and rosemary sprig before serving.