Hash Brown Breakfast Casserole – Cheesy Oven-Baked Brunch

This Hash Brown Breakfast Casserole is the kind of satisfying, one-dish breakfast that feeds a crowd and leaves everyone asking for seconds.

It’s layered with crispy golden hash browns, sautéed mushrooms and onions, tender ham, fluffy eggs, and plenty of melty cheese—finished with fresh tomatoes and herbs for a brunch-worthy touch.

Whether you’re hosting a holiday breakfast, prepping for a busy week, or just want something warm and savory in the morning, this baked breakfast casserole hits all the right notes.

Why You’ll Love This Recipe

Make-ahead friendly – Assemble it the night before and bake fresh in the morning.

Crowd-pleaser – Ham, eggs, cheese, and potatoes? Everyone loves this combo.

Crispy + creamy – Crisp hash browns form the base while the egg custard keeps it moist.

Great use of leftovers – A little ham, a few mushrooms, and it all comes together.

Easy to customize – Swap the meat, add veggies, change up the cheese—it’s flexible and delicious.

What You’ll Need (Ingredient Highlights)

For the Base

Frozen hash browns – The golden, crispy layer that anchors the casserole.

Butter + olive oil – Used to sauté and crisp the hash browns.

For the Filling

Eggs – The main protein and binder.

Sour cream – Adds creaminess and keeps the eggs soft.

Onion + mushrooms – Sautéed for depth of flavor.

Ham – Adds saltiness and texture (sub in bacon, sausage, or skip for vegetarian).

Mexican shredded cheese – Melts beautifully and gives that cheesy pull.

Seasonings – A blend of sea salt, black pepper, and salt-free seasoning like Mrs. Dash.

For the Topping

Cherry or grape tomatoes – Adds fresh color and a burst of brightness.

Chives or cilantro – Herbaceous finish that elevates the whole dish.

Pro Tips Before You Start

Use a cast iron skillet if possible – It crisps hash browns evenly and goes straight into the oven.

Sauté the veggies first – Brings out their sweetness and prevents soggy casserole.

Don’t skip the sour cream – It adds a creamy texture to the eggs.

Whisk the eggs well – A smooth mixture bakes up fluffier.

Let it cool slightly before slicing – Helps the pieces set and makes serving easier.

How to Make Hash Brown Breakfast Casserole

Step 1: Sauté the Vegetables

Preheat oven to 350°F. Heat an 8-inch cast iron skillet (or a sauté pan) over medium heat.

Melt 1 Tbsp butter and sauté ½ cup finely chopped onion until golden.

Transfer to a plate.

Add sliced mushrooms and cook until browned and tender.

Transfer to the same plate.

Step 2: Crisp the Hash Browns

In the same skillet, add 1 Tbsp butter + 1 Tbsp olive oil.

Spread 1 lb frozen hash browns evenly across the bottom.

Cook for about 7 minutes, flipping occasionally, until golden and nearly cooked through.

Remove from heat (or transfer to a greased casserole dish if not using the same pan).

Step 3: Mix the Egg Filling

In a large bowl, whisk together: 6 large eggs, ¼ cup sour cream, ½ tsp Mrs. Dash (or similar seasoning), ½ tsp sea salt, ⅛ tsp black pepper

Stir in the sautéed onions, mushrooms, 4 oz sliced ham, and ½ cup shredded cheese.

Step 4: Assemble and Bake

Pour the egg mixture evenly over the hash browns in the skillet or casserole dish.

Top with the remaining ½ cup shredded cheese.

Cover loosely with foil and bake at 350°F for 25 minutes.

Uncover and bake an additional 5–7 minutes, or until the cheese is melted and lightly golden.

Step 5: Garnish and Serve

Top with halved cherry tomatoes and sprinkle with chopped chives or cilantro.

Let sit for 5 minutes before slicing and serving.

This dish is perfect warm from the oven, but leftovers are just as delicious!

What to Serve With Hash Brown Breakfast Casserole

Fresh fruit salad – Bright and refreshing next to a rich bake.

Crispy bacon or breakfast sausage – If you want to double up on protein.

Avocado slices – Creamy and cooling.

Toasted English muffins – For a crunchy side.

Fresh orange juice or coffee – Breakfast staples that complete the plate.

Variations and Substitutions

Go vegetarian – Skip the ham and add spinach, zucchini, or bell peppers.

Use cooked sausage – For a heartier breakfast.

Try different cheese – Cheddar, mozzarella, or pepper jack all work great.

Make it spicy – Add diced jalapeño to the egg mixture.

Use fresh potatoes – Grate and squeeze dry before crisping like the frozen ones.

Storage Tips

Fridge – Store leftovers covered for up to 4 days.

Freezer – Cool completely, then freeze in slices for up to 2 months.

Reheat – Microwave individual portions or reheat in a 350°F oven until warm.

FAQs

Can I use fresh potatoes instead of frozen hash browns?
Yes! Just shred them and squeeze out as much moisture as possible first.

Can I make this ahead of time?
Yes—assemble it fully, then refrigerate overnight. Bake fresh the next morning.

Can I double the recipe?
Absolutely—just use a larger casserole dish and adjust baking time as needed.

What’s a good dairy-free substitute for sour cream?
Try a plant-based sour cream or plain, unsweetened vegan yogurt.

Can I bake this in a pie dish?
Yes! Just ensure it’s deep enough to hold the filling and adjust the bake time if needed.

Final Thoughts

This Hash Brown Breakfast Casserole is the ultimate all-in-one morning meal—crispy, creamy, cheesy, and loaded with satisfying flavors in every bite.

It’s great for brunch, holiday mornings, or any day you want something warm and hearty without fuss.

Prep it ahead or whip it up fresh—it’s a go-to you’ll come back to again and again.