Name: Cheesy Hash Brown Casserole with Crispy Fried Onions
Prep time: 20 min
Cook time: 50 min
Total time: 1 h 10 min
Cuisine: American
Ingredients: 32 ounces frozen cubed hash browns, thawed; ¼ cup (½ stick) unsalted butter, melted; 2 cups (226 g) sharp cheddar cheese, shredded; 1½ cups (345 g) sour cream; ¼ cup (½ stick) unsalted butter; 1 small yellow onion, diced; 2 teaspoons garlic, minced; ¼ cup (31 g) all-purpose flour; 1 teaspoon kosher salt; ½ teaspoon black pepper; ½ teaspoon cayenne pepper; ½ teaspoon dried mustard; ½ cup (120 g) chicken broth; ½ cup (122.5 g) whole milk; 2 large yellow onions, thinly sliced (about 4 cups); 4 cups (32 ounces) vegetable oil; ½ teaspoon kosher salt

Jump to Recipe·Print Recipe

When it comes to crowd-pleasing casseroles, it’s hard to beat a creamy, cheesy hash brown bake. This Cheesy Hash Brown Casserole with Crispy Fried Onions takes your classic potato casserole to the next level with layers of melty cheddar, a rich homemade sauce, and golden, crunchy fried onions piled on top.

This dish is pure comfort food—warm, creamy, and indulgent with just the right kick of flavor from cayenne and dry mustard. Whether you’re serving it for brunch, a holiday dinner, or just a cozy weeknight meal, it’s guaranteed to steal the show.

Cheesy Hash Brown Casserole with Crispy Fried Onions

Why You’ll Love This Recipe

Ultra cheesy and creamy: Loaded with sharp cheddar and sour cream for a rich, tangy bite.
From-scratch sauce: No canned soups—just real ingredients and bold flavor.
Golden crispy topping: Homemade fried onions add the perfect crunch.
Perfect for feeding a crowd: Fits perfectly in a 9×13 dish and can be doubled.
Freezer and make-ahead friendly: Great for prepping ahead of the holidays or busy weeks.

Ingredients

(Tip: You can find the full list of ingredients and measurements in the recipe card below)

Potatoes:

32 ounces frozen cubed hash browns, thawed
¼ cup (½ stick) unsalted butter, melted
2 cups shredded sharp cheddar cheese
1½ cups sour cream

Sauce:

¼ cup (½ stick) unsalted butter
1 small yellow onion, diced
2 teaspoons garlic, minced
¼ cup all-purpose flour
1 teaspoon kosher salt
½ teaspoon black pepper
½ teaspoon cayenne pepper
½ teaspoon dried mustard
½ cup chicken broth (room temp)
½ cup whole milk (room temp)

Fried Onions:

2 large yellow onions, thinly sliced (about 4 cups)
4 cups vegetable oil
½ teaspoon kosher salt

Instructions

1. Prep the Oven & Dish:

Preheat the oven to 350°F. Spray a 9×13-inch baking dish with nonstick spray and set aside.

2. Mix the Potato Base:

In a large mixing bowl, combine the thawed hash browns, melted butter, shredded cheddar cheese, and sour cream. Stir until everything is evenly mixed. Set aside.

3. Make the Sauce:

In a medium non-stick skillet, melt the butter over medium heat. Add diced onions and cook for 3–5 minutes, or until softened. Add garlic and cook for 1 more minute.

Stir in the flour, kosher salt, black pepper, cayenne pepper, and dried mustard. Cook for another minute to toast the flour.

Slowly whisk in the milk and chicken broth. Continue to whisk until the mixture thickens into a creamy sauce.

4. Assemble and Bake:

Pour the warm sauce over the potato mixture. Stir until well combined, then transfer everything into the prepared baking dish. Spread evenly.

Bake uncovered for 45–50 minutes, or until the casserole is bubbly and golden around the edges.

5. Fry the Onions:

While the casserole is baking, prepare the fried onions. Line a baking sheet with paper towels.

Heat vegetable oil in a deep saucepan to 350°F. Working in small batches, fry about 1 cup of sliced onions at a time for 2–5 minutes, or until golden and crispy. Use a mesh strainer or slotted spoon to remove them and place onto the paper towel-lined tray.

Repeat until all onions are fried. Sprinkle with kosher salt and toss to coat.

6. Finish & Serve:

After the casserole has baked, remove from the oven and immediately top with the crispy fried onions. Serve hot and enjoy!

Variations

Add protein: Stir in cooked bacon, sausage, or diced ham before baking.
Spice it up: Add diced jalapeños or a pinch of red pepper flakes to the sauce.
Swap the topping: Use store-bought French fried onions if you’re short on time.
Make it vegetarian: Swap chicken broth for veggie broth.
Add veggies: Fold in cooked broccoli, peas, or mushrooms for added texture and nutrition.

Heating and Storage Tips

Fridge: Store leftovers in an airtight container in the fridge for up to 4 days.
Freezer: Freeze baked or unbaked (without onions) for up to 2 months. Thaw overnight in the fridge before reheating.
Reheating: Warm in a 350°F oven until hot, about 15–20 minutes. Add fresh onions on top if needed for crunch.

Frequently Asked Questons

Can I use fresh potatoes instead of frozen hash browns?

Yes! Just peel and cube about 3½–4 cups of potatoes. Parboil them first so they cook evenly in the casserole.

Is the homemade sauce necessary?

It really enhances the flavor and texture, but you can substitute with a can of cream of chicken soup in a pinch.

Can I make this ahead of time?

Absolutely. Assemble everything (except for the fried onions) and refrigerate overnight. Bake the next day and top with onions before serving.

How spicy is this dish?

It has a mild kick from the cayenne pepper. You can omit it for a completely mild version or increase it for more heat.

Can I use pre-shredded cheese?

You can, but freshly shredded cheese melts better and gives a creamier texture.

What can I serve this with?

It pairs perfectly with roasted meats, grilled chicken, holiday hams, or a fresh green salad.

Can I air fry the onions instead of deep frying?

Yes! Toss them lightly in oil and air fry at 350°F for 8–10 minutes, shaking halfway through.

Can I use Greek yogurt instead of sour cream?

Yes, Greek yogurt works well as a substitute with a similar tangy flavor.

Will this work in a slow cooker?

Yes! Mix everything in and cook on low for 3–4 hours. Top with onions just before serving.

Can I add more cheese?

Definitely. Add an extra ½ cup for a cheesier casserole, or layer shredded cheese on top before baking.

Conclusion

This Cheesy Hash Brown Casserole with Crispy Fried Onions is everything you want in a side dish—rich, comforting, and completely satisfying. It’s the kind of dish that disappears quickly at family dinners, potlucks, or holiday gatherings. The creamy, cheesy potatoes paired with the golden fried onions hit all the right notes, and once you try it, you’ll keep coming back for more.