Ingredients:

  • 2 lbs frozen shredded hash browns
  • 1/4 cup unsalted butter, melted (for potatoes)
  • 1/4 cup unsalted butter (for sauce)
  • 1 small yellow onion, finely diced
  • 2 Tablespoons all-purpose flour
  • 1 cup whole milk, lukewarm
  • 1 cup full-fat sour cream
  • 2 cups sharp white cheddar cheese, shredded
  • 1 cup Monterey Jack or Gruyère cheese, shredded
  • 1 teaspoon kosher salt
  • 1/2 teaspoon freshly ground black pepper
  • 1/2 teaspoon garlic powder

Instructions:

  1. Thaw the frozen hash browns fully (about 30 minutes). Once thawed, transfer them onto a clean kitchen towel. Gather the edges and twist tightly to squeeze out as much excess liquid as possible. Preheat oven to 375°F (190°C) and generously grease a 9x13 inch baking dish.
  2. Melt the second 1/4 cup of butter in a medium saucepan over medium heat. Add the diced onion and cook until softened and translucent, about 5–7 minutes.
  3. Whisk in the all-purpose flour until fully combined with the butter and onion to form a roux. Cook for 1 minute, stirring constantly, to cook out the raw flour taste.
  4. Slowly stream in the warm whole milk, whisking continuously to prevent lumps. Bring the sauce up to a low simmer and cook until thickened (about 3 minutes), ensuring it coats the back of a spoon.
  5. Remove the pan from the heat. Stir in the sour cream, salt, pepper, and garlic powder.
  6. Add 2 cups of the combined shredded cheese (Cheddar/Monterey Jack), reserving 1 cup for the topping. Stir until the cheese is completely melted and the sauce is smooth and glossy.
  7. Pour the creamy cheese sauce and the 1/4 cup of melted butter (from the Potato Base section) over the thoroughly drained hash browns in the large mixing bowl. Fold gently with a rubber spatula until everything is evenly coated.
  8. Scrape the mixture into the prepared baking dish and spread it into an even layer. Sprinkle the remaining 1 cup of cheese evenly over the top. Cover the dish tightly with aluminium foil.
  9. Bake covered for 30 minutes. Remove the foil and bake for an additional 15–25 minutes, or until the top is bubbling, deep golden brown, and the edges are crispy.
  10. Remove from the oven and allow the casserole to rest for 10 minutes before slicing and serving. This allows the sauce to set properly.