Comfort food at its best, this hearty, tasty au gratin builds on the traditional potatoes au gratin but with lots more nutrient value and a complexity of flavor. Don’t be afraid of the half-cup of heavy cream — the recipe serves six to eight, so the per-serving amount of cream is about a tablespoon. If you’re avoiding dairy, replace the butter with olive oil and the cream with coconut milk. This makes a great Thanksgiving side dish. We demoed this at our October 23, 2013 Brookside Gardens class.
¼ C unsalted butter, divided
2 C leeks, white and light green parts, thinly sliced and well-rinsed
2/3 C apple cider, fresh or hard
½ C heavy cream
2 t fresh thyme leaves, chopped
1 T fresh sage, chopped
Freshly ground black pepper
2 crisp, firm apples, peeled, cored, and sliced
12 oz. butternut squash (neck portion only)
2 medium Yukon Gold potatoes
1½ C Panko breadcrumbs
¾ C grated sharp Cheddar
Prepare the gratin: Heat the oven to 350̊F. Melt the 2 T butter in a small (preferably nonstick) saucepan over medium heat. Add the leeks and a big pinch of salt. Cook, stirring frequently, until well softened and lightly browned (the pan will be dry), 10 to 15 minutes. Add the cider and simmer for 2 minutes to reduce it slightly. Add the cream, the chopped thyme, sage, a pinch of salt, a few grinds of pepper, and stir well; set aside.
Cook the apples: In a large nonstick skillet, melt the remaining 2 T butter over medium heat. Turn the heat to medium high, add the apple slices, and cook, gently flipping and stirring, until most of the slices are browned and limp but not falling apart, about 10 minutes. If the apples begin to stick to the pan as they brown, add a bit of cider to deglaze.
Assemble and bake the gratin: Peel the squash neck, cut it into quarters lengthwise, and cut them across into thin slices. Peel the potatoes (optional), cut them in half, and cut them across into thin slices. In a large bowl, combine the squash slices, the potato slices, the leek mixture, the apple mixture (scrape the pans well), and 1 tsp. sea salt. Using a rubber spatula, mix gently but thoroughly. Scrape the mixture into the prepared gratin dish, smoothing and pressing until evenly distribute. In a separate bowl, mix the Panko with the cheddar. Cover the gratin with the breadcrumb topping.
Bake until the crust is deep golden brown, the juices around the edges have subsided, and the crust is dark brown around the edges, 45 minutes to 1 hour. Let rest for 15 to 20 minutes before serving. Serves 6-8 as a side dish.