📖 Instructions

1. Preheat your oven to 375°F (190°C). This ensures your oven is at the correct temperature for even cooking and a beautiful golden crust. Lightly grease a 9x13-inch baking dish with butter or cooking spray. This step is super important to prevent sticking and make serving easier.
2. Prepare the butternut squash: First, carefully peel the butternut squash using a sturdy vegetable peeler. Now, slice it in half lengthwise, and scoop out those seeds and stringy bits with a spoon. Take your time with this part; you want nice, clean halves. Next, slice the squash into thin, approximately 1/4-inch thick, half-moon shaped pieces. Uniformity here really helps with even cooking!
3. In a large mixing bowl, combine the sliced butternut squash with 3 tablespoons of melted butter, 1/4 cup of pure maple syrup, 1 teaspoon of fresh thyme leaves, 1/2 teaspoon of salt, 1/4 teaspoon of black pepper, and a pinch of grated nutmeg. Gently toss everything together until the squash slices are evenly coated. You want every piece to get some of that lovely maple-thyme goodness.
4. Arrange about half of the seasoned squash slices in a single layer in the prepared baking dish. Don't worry if they overlap a little; they'll soften and settle as they cook. Pour half of the heavy cream (1 cup for 1X serving) evenly over this layer. Sprinkle with half of the Parmesan cheese and half of the Gruyère cheese.
5. Repeat the layering process: Add the remaining squash slices on top, spreading them out as best you can. Pour the rest of the heavy cream over this second layer. Then, sprinkle with the remaining Parmesan and Gruyère cheeses. Make sure the cheese is distributed nicely; this is where that incredible cheesy crust comes from!
6. Prepare the topping: In a small bowl, combine the panko breadcrumbs with 1 tablespoon of melted butter. Mix them together until the breadcrumbs are moistened. Evenly sprinkle this buttery breadcrumb mixture over the top of the gratin. This will give you that irresistible golden, crunchy finish.
7. Bake the gratin: Cover the baking dish loosely with aluminum foil. Place it in the preheated oven and bake for 30 minutes. The foil helps steam the squash, ensuring it gets tender. After 30 minutes, remove the foil and continue baking for another 20-30 minutes, or until the squash is very tender when pierced with a fork, and the top is beautifully golden brown and bubbly. Keep an eye on it – ovens can be quirky!
8. Rest and serve: Once baked, remove the gratin from the oven and let it rest for 5-10 minutes before serving. This brief resting period allows the gratin to set a little, making it easier to serve. Garnish with a few extra fresh thyme sprigs if you like. Serve warm and watch it disappear!