This is a beautiful vegetarian entree or holiday side dish—layers of thinly sliced squash and potatoes in a luscious cream sauce, with a crunchy walnut topping.
- 1 butternut squash (about 2 lb.), peeled
- 2 potatoes, peeled
- 6 Tbl parmesan cheese
- 1 cup heavy cream
- 1/2 cup walnuts, chopped
- 1/2 cup breadcrumbs
- 2 Tbl melted butter
- Heat the oven to 350°F. Grease an 8×8-inch (2-qt.) glass or ceramic baking dish.
- Cut the squash in half lengthwise and scrape out the seeds and fibers.
- Slice the squash and potatoes about 1/8 inch thick (use a mandoline if you have one).
- Line the bottom of the baking dish with a layer of squash (overlapping slightly). Season lightly with salt and pepper, sprinkle with a little of the Parmesan, and drizzle with a little of the cream.
- Cover the squash layer with a layer of potato slices, season with salt, pepper, cheese, and cream.
- Repeat the layers with the remaining squash and potatoes until the baking dish is full, ending with a top layer of squash, seasoned and topped with any remaining cheese and cream. (You may have extra squash.)
- Press down lightly to distribute the cream and compact the layers. The last layer of squash should be just sitting in the cream, but not covered by it.
- Cover the dish with foil and bake until the vegetables feel tender when poked with a thin, sharp knife (be sure to check the middle layer), about 1 hour and 10 min.
- Combine the walnuts, breadcrumbs and butter. Remove the gratin from the oven, sprinkle with the breadcrumb-nut mixture, and bake (uncovered) until the top is lightly browned, 5 to 10 min.
- Let sit in a warm place for 20 min. before serving so that liquids will set and tighten the gratin. Cut into 9 squares and serve.