This Potatoes O’Brien Breakfast Casserole is a hearty dish filled with tasty potatoes, peppers, and fluffy eggs. Perfect for a family breakfast or brunch!
I love how easy it is to throw together! Just mix everything in one pan, bake, and enjoy a warm, filling meal. It’s a great way to start the day! 🍳
Key Ingredients & Substitutions
Frozen Diced Potatoes O’Brien: These potatoes already come mixed with red and green peppers which add flavor and color. If you can’t find them, you can use fresh diced potatoes mixed with sautéed peppers instead.
Breakfast Sausage: This is optional, but it brings great flavor. You could use turkey sausage for a lighter option or skip it altogether if you’re going for a vegetarian dish.
Cheddar Cheese: While cheddar is classic, you can mix it up with Monterey Jack, Pepper Jack for a kick, or even a creamy Swiss. Get creative with your cheese combinations!
Eggs & Milk: For a lighter version, you can use egg whites or egg substitutes. Milk can be swapped with almond milk or oat milk for dairy-free options.
Green Onions: These add a fresh kick. You could use chives or even finely chopped red onion if you don’t have green onions on hand.
How Do You Ensure a Perfectly Cooked Casserole?
Getting the right texture and doneness for your casserole is important. Follow these tips to make sure it turns out great:
- Preheat your oven. Always preheating ensures even cooking right from the start.
- Grease the casserole dish well. This prevents sticking and helps achieve a golden crust.
- Check for doneness. The casserole should be set in the center when done. You can insert a knife to check if it comes out clean.
- Let it cool slightly before serving. This helps it set up a bit, making it easier to cut and serve.
Following these steps will help you create a delicious breakfast casserole every time! Enjoy your cooking!

How to Make Potatoes O’Brien Breakfast Casserole
Ingredients You’ll Need:
For the Casserole:
- 4 cups frozen diced potatoes O’Brien (potatoes with diced red and green bell peppers)
- 1 cup cooked breakfast sausage, crumbled (optional for non-vegetarian version)
- 1 cup shredded cheddar cheese
- 8 large eggs
- 1 cup milk
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper
- 1/2 teaspoon garlic powder
- 1/2 cup diced green onions (plus extra for garnish)
- 4 slices cooked bacon, chopped (optional, for garnish)
How Much Time Will You Need?
This delicious breakfast casserole takes about 15 minutes to prepare and around 35-40 minutes to bake. So, in total, you can expect to spend about an hour from start to finish. Perfect for a hearty breakfast with family or friends!
Step-by-Step Instructions:
1. Prepare the Oven and Dish:
Start by preheating your oven to 350°F (175°C). While the oven warms up, lightly grease a 9×13-inch casserole dish to make sure the casserole doesn’t stick to it.
2. Layer the Potatoes:
Next, spread the frozen diced potatoes O’Brien evenly in the greased casserole dish. This will be the base of your delicious breakfast casserole!
3. Add the Meat (if using):
If you’re using breakfast sausage, sprinkle the cooked, crumbled sausage evenly over the layer of potatoes. This will add a savory flavor that complements the dish!
4. Whisk the Egg Mixture:
In a large mixing bowl, crack the eggs and add the milk, salt, black pepper, and garlic powder. Whisk everything together until the mixture is smooth and well combined.
5. Mix in Cheese and Onions:
Stir in half of the shredded cheddar cheese and half of the diced green onions into your egg mixture. This will give the casserole a nice cheesy flavor with a hint of freshness!
6. Combine Everything:
Pour the egg mixture over the potatoes and sausage in the casserole dish. Use a spoon or spatula to spread it evenly, so every bite is packed with flavor!
7. Add the Final Touch:
Sprinkle the remaining cheddar cheese and green onions over the top of the casserole. This will create a lovely cheesy crust as it bakes!
8. Bake the Casserole:
Place the casserole in the preheated oven and bake it uncovered for 35-40 minutes. You’ll know it’s done when the casserole is set in the center and the top is golden brown.
9. Cool and Serve:
Once it’s finished baking, remove the casserole from the oven and let it cool for a few minutes. This helps it set up better and makes it easier to cut into portions.
10. Garnish and Enjoy:
Before serving, garnish with chopped crispy bacon and any remaining green onions for a lovely presentation. Now, dig in and enjoy your hearty Potatoes O’Brien Breakfast Casserole!
This dish is perfect for breakfast, brunch, or even a cozy dinner. It’s a crowd-pleaser packed with flavor and food that brings everyone together!
Can I Use Fresh Potatoes Instead of Frozen?
Yes, you can! Just make sure to peel and dice the potatoes, then cook them briefly in boiling water or sauté them with oil until slightly tender before adding them to the casserole dish.
How Do I Make This Casserole Vegetarian?
To make a vegetarian version, simply omit the breakfast sausage and bacon. You can add extra vegetables, like spinach or mushrooms, for added flavor and texture!
Can I Prepare This Casserole the Night Before?
Absolutely! You can assemble the casserole the night before, cover it tightly, and store it in the refrigerator. Just make sure to add a few extra minutes to the baking time if going straight from the fridge to the oven in the morning.
What’s the Best Way to Store Leftovers?
Store any leftovers in an airtight container in the refrigerator for up to 3 days. To reheat, warm it in the oven or microwave until heated through. Enjoy for breakfast or as a quick lunch!
