This Cozy Autumn Breakfast Casserole recipe is overflowing with my favorite seasonal roasted veggies and (optional) sausage, it’s easy to make ahead of time, and it’s guaranteed to be the hit of your brunch!
What to do with leftover veggies from my Cozy Autumn Wild Rice Soup recipe?
Why, turn them into a delicious breakfast casserole! ♡
Turns out that this simple seasonal mix of sweet potatoes, kale, mushrooms (if you’d like), garlic, onions and zesty seasoning translates just as perfectly into a cozy autumn breakfast casserole as it does a creamy wild rice soup. Granted, I did also toss in a red pepper and Yukon gold potatoes for a little extra color. Plus some savory sausage, which was delicious but also totally optional if you’d prefer to keep this one vegetarian. And in the end, the result?
Hands-down one of the most delicious breakfast casseroles I’ve ever made.
Plus — bonus! — this one is also super-easy to prep ahead of time. And it’s naturally gluten-free and dairy-free, which can be a little more friendly for serving to a big crowd. So if you’re looking for a stellar and simple breakfast casserole to serve to your loved ones amidst the hustle and bustle of this holiday season, I highly recommend giving this recipe a try. Here’s how to make it!
Cozy Autumn Breakfast Casserole Ingredients:
Alright, to make this breakfast casserole recipe, you will need:
- Autumn Veggies: I used a combination of sweet potatoes, Yukon gold potatoes, baby bella mushrooms, red bell pepper and onion, which we will roast together until tender. But feel free to toss in any other veggies that you like to roast as well. (For example, asparagus, broccoli, cauliflower and/or Brussels sprouts would also be delicious!)
- Kale: Or spinach, or any other greens that you prefer.
- Garlic: For seasoning.
- Sausage: Feel free to use breakfast sausage, Italian sausage (mild, sweet or spicy), or any kind of sausage that you prefer. Or, feel free to sub in bacon or ham. Or just leave out the meat entirely and keep this casserole vegetarian.
- Old Bay Seasoning: I love this zesty seasoning (affiliate link). But if it’s not your favorite, feel free to sub in some Cajun seasoning, Italian seasoning, or whatever you may prefer.
- Eggs: And lots of ’em!
How To Make A Breakfast Casserole:
I’m going to tell you right now — the long list of instructions looks much more complicated than it is! To make this casserole, simply:
- Roast the vegetables. Either on a very large baking sheet, or two medium baking sheets, roast the mushrooms, potatoes, red bell pepper and onion until tender.
- Brown the sausage. Meanwhile, as the veggies are roasting, brown the sausage in a large skillet on the stove. And at the very end, toss in the garlic and kale to give them a quick sauté as well.
- Whisk the eggs. Then, in a separate large bowl or measuring cup, whisk together the eggs, milk, Old Bay seasoning, plus an extra 1 teaspoon salt and 1/2 teaspoon black pepper until combined.
- Assemble the casserole. Then toss the veggies and sausage together in the baking dish, spread them out in an even layer, and drizzle the egg mixture evenly on top of them.
- Bake. Uncovered for about 30 minutes, or until a toothpick inserted in the middle of the casserole comes out completely clean. (If the veggies on top of the casserole get too browned before the casserole is done, just lay a piece of aluminum foil gently on top of the baking dish until the inside is cooked through.)
- Serve warm. Then slice, serve, and enjoy!
Want to mix things up with this breakfast casserole recipe? Feel free to either:
- Make it vegetarian. You can either use vegan sausage (I really love Italian Field Roast), or nix the sausage entirely.
- Make it spicy. I love using spicy Italian sausage for an extra kick, or you can also add in a few pinches of crushed red pepper flakes.
- Add cheese. Honestly, this casserole is impressively flavorful and creamy without the cheese. But feel free to add in any shredded cheeses that you love. (I would recommend about 1 cup shredded cheese.) Or crumbled soft cheeses such as goat, feta or blue cheese would be delicious too. (I would recommend about 1/2 cup crumbled soft cheese.)
- Vary the seasonal veggies. If you’re not making this recipe in the autumn or winter, feel free to sub in whatever seasonal roasted veggies that you love.
To make this breakfast casserole ahead of time, simply follow the recipe instructions below through step 5 (pouring in the egg mixture). Then cover the baking dish snugly with plastic wrap or foil, and refrigerate for up to 24 hours. Once you’re ready to bake the casserole, let it rest on the counter for 30 minutes or until it nearly reaches room temperature. Then bake as directed.
This Cozy Autumn Breakfast Casserole recipe is overflowing with my favorite seasonal roasted veggies and (optional) sausage. See notes above for possible variations, plus tips on how to prep this casserole ahead of time.
- 8 ounces baby bella mushrooms, quartered
- 1.5 pounds potatoes, diced into 1/2-inch cubes (I used half sweet potatoes, half Yukon gold)
- 1 large red bell pepper, cored and diced
- 1 medium white or yellow onion, peeled and diced
- 3 tablespoons olive oil
- sea salt and freshly-cracked black pepper
- 1 pound ground Italian sausage (or breakfast sausage)
- 4 cloves garlic, peeled and minced
- 2 handfuls roughly-chopped fresh kale, tough stems discarded
- 15 eggs, whisked
- 2/3 cup milk
- 1 1/2 tablespoons Old Bay Seasoning, or more/less to taste
- Prep oven and baking pan. Heat oven to 400°F. Line a large baking sheet (or two medium baking sheets) with parchment paper; set aside. Lightly mist a 9 x 13-inch baking pan with cooking spray; set aside.
- Roast the vegetables. Spread the mushrooms, potatoes, red bell pepper, and onion out on a large baking sheet (or two medium baking sheets). Drizzle evenly with the oil, and season with a few generous pinches of salt and pepper. Toss the veggies until they are evenly coated with the oil and arranged in an even layer, not overlapping. Bake for about 20-25 minutes, or until the potatoes are tender. Remove baking sheet(s) from the oven, and carefully transfer the veggies into the prepared baking dish; set aside.
- Brown the sausage. Meanwhile, as the veggies are roasting, cook the sausage in a large sauté pan over medium-high heat until browned, using a wooden spoon to break up and crumble the sausage as it cooks. Once the sausage is browned, add in the garlic and kale and sauté for an extra 2-3 minutes, stirring occasionally, until fragrant. (If there is not leftover oil in the pan from the sausage, you may need to add in an extra teaspoon or two to sauté the garlic and kale.) Remove pan from heat, and transfer the sausage into the prepared baking dish; set aside.
- Whisk the eggs. In a separate large bowl or measuring cup, whisk together the eggs, milk, Old Bay seasoning, plus an extra 1 teaspoon salt and 1/2 teaspoon black pepper until combined.
- Assemble the casserole. Once the veggies and sausage have been cooked and added to the baking dish, use a spoon to give them a brief toss. Then spread the mixture out in an even layer in the baking dish. Carefully pour the whisked egg mixture evenly on top of the veggies and sausage.
- Bake. Bake uncovered for 30-35 minutes, or until a toothpick inserted in the middle of the casserole comes out completely clean. (If the veggies on top of the casserole get too browned before the casserole is done, just lay a piece of aluminum foil gently on top of the baking dish until the inside is cooked through.) Remove from the oven and transfer to a cooling rack to cool for 10 minutes.
- Serve warm. Then slice, serve, and enjoy! Or cover and refrigerate for up to 3 days.
*If making this recipe gluten-free, be sure to use all certified gluten-free ingredients. If making this recipe dairy-free, just use your favorite plain non-dairy milk.