1. Preheat oven to 400°. Arrange bread cubes on a baking sheet, and bake at 400° for 10 to 12 minutes or until lightly browned and toasted. Set aside to cool slightly. Increase oven temperature to 450°.
2. Mound squash and shallot in the center of a rimmed baking sheet. Whisk together salt and next 3 ingredients in a small bowl. Pour over mounded squash and shallot, and toss to coat. Spread vegetables in a single layer on the sheet, using 2 sheets if necessary.
3. Roast at 450° for 20 minutes or until tender when pierced. Shake the sheet halfway through cooking. Toss warm squash in a bowl with reserved croutons and sage. Spread on a heated platter, and cover to keep warm until ready to serve.