Prime Rib Breakfast Casserole
If you’ve got leftover prime rib hanging out in the fridge and you’re wondering how to use it, let me introduce you to your next favorite breakfast: Leftover Prime Rib Breakfast Casserole.
This casserole recipe is rich, cheesy, and packed with tender bites of leftover prime rib and hashbrowns, all baked into a silky egg custard. It’s exactly the kind of easy, comforting dish you want the morning after a holiday.
If you prefer a quicker Christmas breakfast, make this breakfast skillet, but sub in prime rib for the sausage.
Ingredients And Substitutions
These are the key ingredients you’ll need for this breakfast casserole. You’ll find the full ingredient list in the recipe card below.
Leftover Prime Rib: Any leftovers from my collection of standing rib roast recipes will work: No Peek Prime Rib, Reverse Seared Prime Rib, Smoked Prime Rib, or Sous Vide Prime Rib.
Cheese: Use whatever melts well: cheddar, gouda, mozzarella, pepper jack, Monterey Jack, or a combination.
Hashbrowns: Make sure to put the hashbrowns in the refrigerator overnight to defrost. I haven’t tested this with frozen hashbrowns yet – but it’s on the “to do” list! Leave a comment below if you try it! You can also use small tater tots if you have those on hand.
Milk: You can replace any portion of the milk with half and half or whole cream.
Would you like to save this?
We'll email this post to you, so you can come back to it later!
Variations
This breakfast casserole recipe is endlessly adaptable. Try one of these combinations to switch things up:
- Swiss + Mushrooms for something rich and cozy
- Cheddar + Jalapeño to add a spicy kick
- Garlic + Fresh Herbs like rosemary or thyme
Recipe Tips
- If your roast has a bold prime rib seasoning rub (like heavy peppercorn or horseradish rub), trim the edges if you’re worried about the flavors overpowering the casserole.
- This hashbrown breakfast casserole can be prepped the night before and stored in the fridge until ready to bake.
- Leftovers refrigerate beautifully! Store in the fridge for 3–4 days or freeze slices individually for a quick grab-and-reheat breakfast.
More Prime Rib Leftover Recipes
Here are a few more leftover prime rib ideas to try:
Leftover Prime Rib Breakfast Casserole
Ingredients
- 20 oz shredded hashbrowns, thawed
- 2 cups cubed leftover prime rib
- 2 cups shredded cheese (*Note 1)
- ½ cup chopped green onion, + more for garnish
- 8 large eggs
- 1 cup milk
- ½ tsp dijon mustard
- ½ tsp Worcestershire sauce
- ½ tsp garlic powder
- ¼ tsp salt
- ¼ tsp ground black pepper
- ½ tsp Optional: steak sauce (*Note 2)
Instructions
- Preheat oven to 350°F.
- Grease a 9×13 casserole dish and evenly distribute hashbrowns across the bottom of the dish.
- Evenly distribute the prime rib, cheese, then chopped onions over the hashbrowns.
- In a large mixing bowl, add eggs, milk, garlic powder, mustard, Worcestershire sauce, steak sauce, salt, and pepper, and whisk to combine. Carefully pour the egg mixture over the top of the prime rib/hash browns.
- Bake for 45-55 minutes or until cooked throughout. Remove from oven and let rest for 5-10 minutes to set.
- Top with green onions, if desired, slice, and serve.