Could you tell me how to prepare Butternut Squash Au Gratin?
Here's a recipe for Butternut Squash Au Gratin:

Ingredients:

Gratin

• 1 tablespoon unsalted butter
• 2 cloves garlic, minced
• 1 tablespoon all purpose flour
• 1 cup milk
• 1 can Campbell's® Cream of Chicken Soup
• 1/4 teaspoon onion powder
• 1/4 teaspoon kosher salt
• 1/4 teaspoon freshly ground black pepper
• 1 teaspoon fresh thyme leaf, roughly chopped (option to use dried)

• 1/2 cup shredded sharp cheddar cheese
• 1/2 cup shredded gruyère cheese
• 1/4 cup grated parmesan cheese
• 1 butternut squash, halved lengthwise and sliced into ⅛-inch-thick slices

For Topping

• 1/2 cup shredded sharp cheddar cheese
• 1/2 cup shredded gruyère cheese
• 1/3 cup seasoned bread crumbs
• 1 tablespoon fresh thyme leaf, roughly chopped (option to use dried)

Instructions:

1. Preheat the oven to 425°F (220°C).
2. Melt the butter in a medium saucepan over medium-low heat. Add the garlic and cook until fragrant, about 1 minute. Add the flour and stir for 1 minute more, or until the flour turns light golden brown in color. Slowly pour the milk, stirring constantly, and cook, still stirring, until the mixture thickens slightly, 2–3 minutes.
3. Add the Campbell’s® Cream of Chicken Soup and stir to combine. Add the onion powder; salt; pepper; thyme; and the cheddar, Gruyère, and Parmesan cheeses. Stir for about 2 minutes, or until the cheese has melted completely. Remove the pot from the heat.
4. Arrange 1/3 of the butternut squash slices on the bottom of an 8-inch square baking dish. Spread 1/3 of the sauce on top of the squash. Repeat with the remaining squash and sauce to make 2 more layers.
5. Bake the gratin for 35 minutes, until the butternut squash is tender.
6. Remove the gratin from the oven and turn the broiler on high.
7. Sprinkle the cheddar and Gruyère cheeses over the gratin in an even layer. Top with the bread crumbs and thyme.
8. Return the gratin to the oven and broil until the cheese is melted and the bread crumbs are toasted, 1–3 minutes. Keep a close eye on the dish to prevent burning.
9. Allow the gratin to cool for about 10 minutes before slicing and serving.

Enjoy your Butternut Squash Au Gratin!