Description

Want to wake up to a hot, hearty breakfast without morning stress? This Overnight Breakfast Casserole is the ultimate make-ahead dish. Loaded with eggs, bread, veggies, and melty cheese, it’s a savory, comforting breakfast that feeds a crowd with zero fuss in the morning. Just prep it the night before, refrigerate, and bake when you’re ready to enjoy!

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Ingredients

Scale

For the Casserole Base:

6 large eggs
2 cups milk (dairy or plant-based)
1 tsp Dijon mustard (adds depth)
Salt and black pepper, to taste
6–8 slices whole grain or sourdough bread, cubed
1 ½ cups shredded cheese (cheddar, mozzarella, or your favorite blend)
1 cup cooked and crumbled chicken sausage or ground beef (optional)
1 bell pepper, diced
1 cup spinach or kale, chopped
½ cup red onion, finely diced
Optional: ½ tsp garlic powder or Italian seasoning

For Topping (optional):

¼ cup grated Parmesan cheese
Fresh chives or parsley for garnish
Sliced cherry tomatoes

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Instructions

Step 1: Prepare the Ingredients

Lightly grease your baking dish.
Dice the vegetables and cube the bread into bite-sized pieces.
If using meat, cook and crumble it, then set aside to cool.

Step 2: Make the Egg Mixture

In a large bowl, whisk together eggs, milk, Dijon mustard, salt, pepper, and optional garlic or herbs.
Whisk until well combined and smooth.

Step 3: Assemble the Casserole

Spread half of the bread cubes in the bottom of the baking dish.
Layer with half the veggies, meat (if using), and cheese.
Repeat the layers with remaining bread, veggies, meat, and cheese.
Pour the egg mixture evenly over the top, pressing down gently so all the bread is soaked.

Step 4: Cover and Chill Overnight

Cover the dish tightly with foil or plastic wrap.
Refrigerate for at least 6 hours or overnight.

Step 5: Bake in the Morning

Preheat your oven to 175°C (350°F).
Remove casserole from the fridge and let sit at room temp for 20–30 minutes.
Uncover and sprinkle with Parmesan and optional tomato slices.
Bake for 45–50 minutes until the center is set and top is golden.
Let rest for 5–10 minutes before slicing.

Notes

Use Sturdy Bread – Day-old sourdough or whole grain bread works best.
Don’t Skip Soaking – Overnight chilling lets the bread absorb all the flavor.
Prep in Advance – You can prep 1–2 days ahead and bake fresh.
Balance Textures – Mix soft veggies with crunchy toppings or seeds.
Let It Rest – This helps the casserole hold together for clean slices.

Prep Time: 15 minutes
Cuisine: American