An easy to prepare sourdough hash brown casserole, perfect on it's own or as a tasty side dish for your next breakfast or brunch. You can use fresh shredded potatoes or frozen hash browns, it's up to you.

Sourdough starter is used to thicken the cheesy white sauce used to bring this casserole together.

If you love sourdough breakfast recipes, then make sure you check out this sourdough breakfast casserole, sourdough discard sheet pan pancakes or these sourdough bagels.

Sourdough hash brown casserole baked in a 9" x 13" baking dish and topped with green onions.

Why You'll Love This Recipe!

Feed A Crowd - This is the perfect sourdough breakfast casserole to feed a crowd! It can be made ahead of time and stored in the refrigerator and is perfect on it's own or as a tasty breakfast side dish.

Uses 150g of Sourdough Discard - You can add 150g of sourdough starter or sourdough starter discard to this sourdough hash brown casserole to thicken the white sauce. It's such a great way to use up your discard in a unique way (and similar to this sourdough mac and cheese).

A baking dish containing sourdough hash brown casserole made with sourdough discard and potatoes. It is golden brown on top and is topped with chopped green onions.

Sourdough Discard or Sourdough Starter

This recipe is a great way to use up your sourdough discard. Although you can also use fresh, recently fed active starter if you prefer. It doesn't make any difference because you aren't using the sourdough starter for leavening at all. The sourdough component is used to thicken the white sauce in this recipe. You can read about the differences between sourdough starter and sourdough discard here.

The sourdough starter in this recipe is used instead of adding all purpose flour. Sourdough recipes that don't use added flour are very handy if you've run out of flour or you just don't want to use more when utilising your sourdough discard. You can read about how to add sourdough discard to any recipe here.

How To Make Sourdough Hash Brown Casserole

This easy sourdough hash brown casserole uses simple ingredients you would normally have in your pantry and fridge. It's a great sourdough recipe to have in your collection if you have lots of potatoes to use up (like we do when my husband harvests our potato patch).

Flat lay of ingredients necessary to make a sourdough hash brown casserole.

Preheat your oven to 200C (390F) and grab a 9 x 13" baking dish (this dish is a little deep however I find it saves the white sauce spilling over into the bottom of the oven).

Grate the potatoes using a box grater (I have chosen to leave the skin on but you can peel yours if you prefer). Place the grated potato onto a flour sack tea towel and squeeze out as much liquid as you can. Set the potatoes aside in the dish towel while you prepare the other ingredients.

A pile of shredded potato sitting in a white flour cloth tea towel ready to make a sourdough hash brown casserole.

In a medium sized saucepan, melt the butter gently. Once the butter is melted, add the sourdough starter and whisk until combined. Then add the milk on top and whisk over a medium heat until the sauce thickens. Add the pepper, salt and onion powder and whisk until well combined. Depending on which type of pepper you use, the sauce might look a grey or brown color - don't stress, it will be fine!

Now take the saucepan off the heat and whisk the sour cream through the white sauce you've just made. Set this aside for now.

In a large bowl, add the potatoes and about ¾ of the cheese and stir together until well distributed. Now pour the white sauce into the bowl and stir through the potato and cheese mixture.

Pour the potato mixture into your baking dish. Top with the remaining cheese and breadcrumbs (if using). Cover with foil and place into the oven for 45 minutes.

A sourdough hash brown casserole topped with cheddar cheese ready to go into the oven.

Once 45 minutes has passed, remove the aluminium foil and place back into the oven to brown for 15 minutes (increase the temperature to 220C (430F) for this bit to ensure the top browns).

Once golden brown and bubbly on top, remove from the oven and allow to sit for 15 minutes before serving. This allows the sauce to thicken and the casserole to "set" before you serve it.

We love serving it as a side dish to bacon and eggs on a weekend morning.

How To Store + Freeze

This sourdough hash brown casserole can be made up to 2 days ahead and stored in the refrigerator. Bake it and then allow to cool and wrap in aluminum foil. Warm through in a moderate oven, uncovered, before serving.

Leftovers can be stored in an airtight container in the fridge for up to 3 days.

You can freeze this recipe. Once baked and cooled, cover the baking dish in aluminium foil (I do a double layer). Store in the freezer for up to 2 months. Allow to thaw overnight in the fridge or at room temperature for a few hours. Warm through in a moderate oven before serving.