Say goodbye to boring vegetable sides, both at Thanksgiving and every meal after! Butternut Squash Gratin transforms and elevates a traditional holiday side into the creamiest, melt-in-your-mouth casserole ever! The sweet nuttiness of the butternut squash plays with the onion flavors of sautéed leeks and garlic and the rich saltiness of Gruyère cheese. With toasted walnuts and crispy sage on top for a wonderful crunch and a burst of garden flavors, this vegetable dish offers a hearty, rustic feast of the senses… perfect for your holiday feast!
Ingredients
- 1 (2-pound) butternut squash, peeled, deseeded, and sliced to 1/8-inch disks
- 2 tablespoons olive oil or butter
- 2 medium leeks, rinsed and thinly sliced
- 4 garlic cloves, roughly chopped
- 15 sage leaves, chopped
- 1 cup heavy cream
- 1/2 teaspoon salt, plus a pinch
- 1/2 teaspoon pepper
- 1/2 teaspoon nutmeg
- 1/2 teaspoon onion powder, optional
- 1/4 cup water
- 3 ounces Gruyère cheese
- 1/2 cup toasted walnuts, chopped
For the crispy sage garnish, optional:
- 1 tablespoon butter or olive oil
- 8 sage leaves
Directions
Step 1 –Preheat your oven to 375 degrees F.
Step 2 –Set aside 12-15 of the most visually appealing butternut squash slices to use for topping the gratin. Any “less appealing” slices will go in the middle layer.
Step 3 –Heat the butter or oil in a large skillet over medium heat.
Step 4 –Sauté the leeks, covering the skillet halfway through cooking to soften them, for 8-10 minutes.
Step 5 –Add in the sage, garlic, and a pinch of salt, cooking for an additional 2-3 minutes. Then turn off the heat.
Step 6 –In a separate medium bowl, whisk the heavy cream with the pepper, 1/2 teaspoon salt, onion powder, and nutmeg. Set aside.
Step 7 –Grease a large 9×13-inch baking dish with nonstick cooking spray. We recommend using a big, shallow pan for the optimal outcome.
Step 8 –After greasing the pan, pour in the 1/4 cup of water.
Step 9 –Layer the bottom of the pan with the butternut squash slices, slightly overlapping each other.
Step 10 –Top with half of the sautéed leeks.
Step 11 –Then pour in about 1/3 cup of the cream mixture.
Step 12 –Sprinkle 1 ounce of the grated Gruyère cheese on top, about 3-4 tablespoons.
Step 13 –Repeat these steps, putting the least appealing butternut squash slices with the remaining sautéed leaks in the middle, and then continuing to build up. The topmost layer should consist of the cream mixture and the remaining cheese.
Step 14 –Lightly sprinkle the top with the walnuts.
Step 15 –Gently shake the pan, pressing down on the center to ensure that the center will not form a dome.
Step 16 –Cover, using parchment paper first, then foil over the top. Bake, covered, for 45 minutes.
Step 17 –After 45 minutes of cooking, carefully uncover the casserole and check if the butternut squash is tender using the tip of a knife. If not tender, cook for a few more minutes before proceeding with the next step.
Step 18 –If tender, then increase the temperature of the oven to 400 degrees F and bake for an additional 15 minutes, uncovered, until golden.
Step 19 –Meanwhile, in a pan over medium heat, heat 1 tablespoon of butter or oil to begin preparing the crispy sage garnish.
Step 20 –Add the whole sage leaves once the butter is melted or the oil is simmering, sautéing each side until nice and crisp, for approximately 30 seconds.
Step 21 –Then set the leaves onto a paper towel, allowing them to cool for a couple of minutes.
Step 22 –Once the gratin is finished cooking, remove it from the oven and arrange the crispy sage leaf garnish over the top, to your liking.
Step 23 –Serve warm!