My Cheesy Spinach Breakfast Casserole for Busy Mornings

Is there anything better than a cozy, savory breakfast that practically makes itself? You know the kind—the one that fills your kitchen with the most incredible smell and gives everyone a warm, happy start to the day. That’s the magic of this Cheesy Spinach Breakfast Casserole. It’s the hero of weekend brunches and the secret weapon for busy weekday mornings when you need a make-ahead meal that’s both nourishing and delicious. Honestly, it’s the one dish that makes me look forward to my alarm clock.

Why You’ll Love This

This casserole is the ultimate crowd-pleaser. It’s so, so comforting, packed with protein to keep you full, and loaded with cheesy goodness that even the pickiest eaters will adore. The best part? You can assemble it the night before. Just pop it in the oven in the morning, and by the time you’ve poured the coffee, breakfast is ready. It’s a perfect solution for a breakfast buffet when you have guests, or for giving your family a hot, healthy breakfast without the morning rush. It’s a simple breakfast idea that feels anything but basic.

Ingredients You’ll Need

• 10 large eggs: The protein-packed base that gives the casserole its structure.
• 1 cup whole milk: Adds creaminess and helps create a soft, fluffy texture.
• 1 cup cottage cheese (small curd): A little trick for extra protein and a wonderfully moist result.
• 8 ounces shredded sharp cheddar cheese: For that classic, melty, cheesy flavor we all crave.
• 4 ounces shredded mozzarella cheese: Adds that incredible stretchy, gooey factor.
• 1 (10-ounce) package frozen chopped spinach, thawed and squeezed dry: Crucial for squeezing out all the water so your casserole isn’t soggy!
• 1 small yellow onion, diced: Brings a sweet, savory depth of flavor.
• 1 red bell pepper, diced: Adds a pop of color and a hint of sweetness.
• 6 slices of bread, cubed (about 4 cups): Stale bread works great here, forming a hearty base.
• 1 teaspoon garlic powder: For a touch of savory flavor without any chopping.
• 1 teaspoon dried mustard: A secret ingredient that enhances the cheesiness.
• 1/2 teaspoon salt, plus more to taste: To season everything perfectly.
• 1/4 teaspoon black pepper: For a little bite.
• Cooking spray or butter: For greasing the baking dish.

Let’s Get Cooking Step by Step

1. First, preheat your oven to 350°F (175°C). Grab a 9×13-inch baking dish and give it a good coating of cooking spray or butter. This is your insurance policy for easy cleanup later!
2. Now, spread your cubed bread evenly across the bottom of the prepared dish. This will become the satisfying, hearty foundation of your casserole.
3. In a large mixing bowl, it’s time for the wet ingredients. Whisk the eggs, milk, cottage cheese, garlic powder, dried mustard, salt, and pepper together. You want to whisk until it’s all nice and smooth, with no big streaks of egg white or clumps of cottage cheese.
4. Let’s add the good stuff! Stir in the shredded cheddar, mozzarella, the squeezed-dry spinach, diced onion, and red bell pepper. Mix it all up until everything is beautifully combined and coated in the egg mixture.
5. Carefully pour this cheesy, eggy mixture over the bread cubes in your baking dish. Use a spatula to gently press down on any bread pieces that are poking out, making sure they get soaked in the liquid. This ensures every single bite is moist and delicious.
6. Pop the dish into your preheated oven and bake for 45-55 minutes. You’ll know it’s done when the top is a gorgeous golden brown and the center is set. A great test is to give the pan a slight jiggle; if the center doesn’t wobble much, it’s ready. For an extra-cheesy top, you can sprinkle a little more shredded cheese on during the last 5 minutes of baking.
7. This is the hardest part: let it rest! Allow the casserole to sit for about 5-10 minutes before you cut into it. This helps it firm up so you get clean, beautiful squares.

Cheesy Spinach Casserole Tips For Success

• Don’t skip squeezing the spinach! This is the single most important step to avoid a watery casserole. Get in there with your hands and press out every last drop of liquid.
• Feel free to use different bread. A sturdy sourdough, whole wheat, or even a day-old baguette all work wonderfully.
• For a shortcut, you can use a bag of frozen diced onions and peppers to save on prep time.
• Got a few extra minutes? Sauté the onion and bell pepper in a little butter before adding them to the mix. It deepens their flavor incredibly.
• If you’re making this ahead, mix everything, pour it into the dish, cover it tightly, and refrigerate overnight. In the morning, just bake it straight from the fridge, adding a few extra minutes to the baking time if needed.
• And my personal favorite tip? A little dash of hot sauce stirred into the egg mixture adds a delightful zing. So good.

Variations & Substitutions

This recipe is like a blank canvas for your morning cravings.

• Meat Lovers: Add about a cup of cooked, crumbled breakfast sausage or diced smoked turkey sausage for a heartier dish.
• Mushroom & Swiss: Swap the cheddar for Swiss cheese and add a cup of sautéed sliced mushrooms.
• Sun-Dried Tomato: Stir in 1/2 cup of chopped sun-dried tomatoes (the kind packed in oil, drained) for a sweet, tangy burst.
• Dairy-Free? Use your favorite unsweetened non-dairy milk, a dairy-free cheese alternative, and omit the cottage cheese or use a soft tofu blend.
• Gluten-Free? Simply use your preferred gluten-free bread cubes.
• Lower Carb? You can omit the bread entirely. The result will be more like a crustless quiche, but still utterly delicious.

Storage & Reheating

This casserole is a meal-prep dream. Let any leftovers cool completely, then store them in an airtight container in the refrigerator for up to 4 days. To reheat, I find the microwave works just fine for a quick single serving. But for the best texture, reheat slices in a 350°F oven or a toaster oven for about 10-15 minutes, until warm all the way through. You can also freeze this casserole! Wrap individual portions or the whole thing tightly in plastic wrap and then aluminum foil. It will keep well for up to 2 months. Thaw overnight in the refrigerator before reheating.

Serving Ideas & Pairings

This Cheesy Spinach Breakfast Casserole is a star all on its own. But it also loves company! For a full breakfast buffet spread, serve it alongside a big bowl of fresh fruit, some crispy bacon or turkey sausage links, and a basket of warm muffins or biscuits. If you’re leaning into savory breakfast vibes, a simple arugula salad with a lemon vinaigrette on the side is a fantastic, fresh contrast. And of course, don’t forget the coffee, orange juice, or a pot of hot tea.

Frequently Asked Questions

• Can I use fresh spinach instead of frozen? Absolutely! You’ll need about 10 ounces of fresh spinach. Just give it a rough chop and wilt it in a pan with a tiny bit of water or oil before squeezing it dry and adding it to the mix.
• I’m not a fan of cottage cheese. Can I leave it out? You can, but it really does add moisture and protein without a strong flavor. If you skip it, you might want to add an extra egg or a bit more milk to keep the texture right.
• What are some other healthy breakfast recipes I can try? If you love this, you might also enjoy a veggie-packed frittata, overnight oats with berries, or simple breakfast ideas like avocado toast with a fried egg. Healthy food ideas are all about finding what makes you feel good!
• How can I tell if the eggs are fully cooked? The casserole should be puffed up and golden on top, and the center should not jiggle loosely when you gently shake the pan. You can also insert a knife into the center; if it comes out clean, it’s done.