Butternut-Squash and Kale Gratin

Preheat oven to 400 degrees. Slice squash just above bulb. Slice squash neck crosswise into 1/4-inch rounds. Cut squash bulb in half lengthwise. Remove seeds with a spoon; discard. Slice each half crosswise into 1/4-inch half-moons.

Set a steamer basket in a large pot filled with 1 inch water; bring to a boil. Add kale, cover, and steam until bright green and wilted, about 3 minutes. Remove from heat; let cool slightly. Squeeze dry.

Butter a shallow 4-quart baking dish (13 by 9 inches). Arrange half of sliced squash in dish, shingling pieces to overlap. Season with salt and pepper. Top with kale, season with more salt and pepper, and sprinkle with 1/2 cup Parmesan and 2 tablespoons sage. Place remaining squash on top, overlapping pieces slightly; season with more salt and pepper. Pour cream over squash and sprinkle with remaining 2 tablespoons sage.

Cover tightly with parchment-lined foil and bake until squash is tender, about 40 minutes. Uncover and sprinkle with panko and remaining 1/4 cup Parmesan. Bake, uncovered, until golden, 10 to 15 minutes more. Let cool slightly before serving.