Preheat oven to 400°. Peel squash. Cut lengthwise in half; remove and discard seeds. Place squash in a 13×9-in. baking pan / shallow roasting pan, cut side down. Drizzle with oil and sprinkle with salt. Bake, uncovered, 20 minutes. Let cool 15 minutes.
Cut squash crosswise into 1/8-in. slices, leaving them intact at the bottom. Combine remaining ingredients; brush over squash. Bake until tender, 30-40 minutes longer. If desired, top with fried sage leaves.