Hash Brown Casserole

"This cozy dish of tender potatoes, cheesy with sharp Cheddar and rich with sour cream, easily feeds a crowd for brunch or a holiday potluck. Store-bought frozen hash browns do most of the work here, but you also can use frozen cubed potatoes. Traditionally, this casserole, also known as “funeral potatoes”, is made with canned cream of chicken soup, but this version calls for making the soup from scratch. While that may sound fussy, the homemade soup comes together in less than 10 minutes — and of course you can use a 10-ounce can of soup instead. For extra crunch, be sure to try the optional cornflakes topping. "

https://cooking.nytimes.com/recipes/1024810-hash-brown-casserole

For the Casserole

• 1 (30-ounce) bag frozen shredded hash browns
• 1 1tablespoons unsalted butter
• 4 tablespoons all-purpose flour
• ¾ cup whole milk
• ¾ cup chicken stock
• Kosher salt (such as Diamond Crystal) and black pepper
• ¼ teaspoon onion powder
• ¼ teaspoon garlic powder
• ¼ teaspoon celery salt
• 1 cup sour cream (8 ounces)
• 1 small yellow onion, finely chopped
• ½ cup shredded or grated Parmesan (1½ ounces; optional)
• 2 cups grated sharp yellow Cheddar (8 ounces; see Tip)
• Chopped parsley, to serve (optional)

For the Topping (optional)

• 2 cups cornflakes, crushed
• 2 tablespoons unsalted butter, melted

1. Step 1

   Prepare the casserole: Remove the frozen hash browns from the freezer and set aside. Heat the oven to 350 degrees with the rack in the center position.

2. Step 2

   Prepare the cream of chicken soup: In a medium saucepan, melt 3 tablespoons butter over medium. Whisk in 2 tablespoons flour until smooth; repeat with the remaining 2 tablespoons flour. Continuously whisk the butter-flour mixture (known as roux) to cook off the raw scent of the flour, about 1 minute. Slowly pour in the milk, whisking continuously, until thickened, about 1 minute. Slowly pour in the chicken stock, whisking continuously. Add ½ teaspoon salt, ½ teaspoon black pepper, the onion powder, garlic powder and celery salt. Stir continuously, until thickened and the mixture coats the back of a spoon, about 3 minutes. Remove from the heat, taste and adjust seasonings. Set aside to cool slightly.

3. Step 3

   Melt the remaining 8 tablespoons of butter. Grease the bottom of a 9-by-13-inch casserole dish with about 2 tablespoons of the melted butter, swirling it around.

4. Step 4

   To a large bowl, add the rest of the butter, the homemade cream of chicken soup and sour cream and whisk to mix. Add the onion, Parmesan (if using) and two-thirds of the Cheddar. Stir and season with 1 teaspoon each salt and pepper. Add the hash browns, gently breaking them up by hand if they’re still frozen in a solid block. Stir until everything is well combined. Watch out here - I don't think it needs the extra 1 teaspoon salt - I wonder if this was a typo - it seemed plenty salty at this point!!
   

5. Step 5

   Add the hash brown mixture to the casserole dish, spread evenly and top with the remaining Cheddar.

6. Step 6

   Prepare the topping (if using): Toss the crushed cornflakes with the butter and sprinkle on top of the casserole.

7. Step 7

   Bake the casserole uncovered until bubbling at the bottom and beginning to crisp and brown around the edges, about 1 hour. If the optional topping browns too quickly, tent the top with foil. Let sit for 10 minutes, then garnish with parsley if you’d like and serve.

Tips

• To make ahead, cool the baked casserole to room temperature, then cover tightly and refrigerate for up to 3 days or freeze for up to 3 months. Reheat uncovered in a 350-degree oven until warmed through and bubbly.
• You can substitute 1 cup of shredded mozzarella for 1 cup of Cheddar.