There’s something magical about waking up to a hearty, delicious breakfast that’s already prepared. If you’re looking for a stress-free start to your morning, this Vegetarian Overnight Breakfast Casserole is your new best friend.
Packed with wholesome vegetables, melty cheese, and fluffy eggs, it’s perfect for busy weekdays, special brunches, or feeding a crowd with minimal effort. By assembling everything the night before, you’ll let all the flavors meld together, and all that’s left in the morning is to pop it in the oven.
Whether you’re a dedicated vegetarian or simply trying to add more plant-based meals to your diet, this casserole is sure to become a staple in your breakfast routine.
Best of all, this recipe is endlessly customizable. You can swap in your favorite veggies, add different cheeses, or use various breads to suit your taste.
It’s an excellent way to use up leftovers, sneak in extra nutrition, and make mornings a little easier. Let’s dive into why you’ll love this overnight vegetarian breakfast casserole!
Why You’ll Love This Recipe
- Convenient Make-Ahead: Assemble everything the night before and bake in the morning—no need to rush!
- Customizable: Use whatever vegetables, cheeses, or bread you have on hand.
- Hearty & Filling: Packed with protein and fiber to keep you satisfied for hours.
- Family-Friendly: Both kids and adults love the cheesy, savory goodness.
- Perfect for Entertaining: Ideal for brunches, holidays, or meal prep.
- Vegetarian-Friendly: No meat, but tons of flavor and nutrition.
- Easy Cleanup: Everything bakes in one dish!
Ingredients
| Ingredient | Amount | Notes |
|---|---|---|
| Crusty bread | 6 cups, cubed | Use day-old or slightly stale bread for best texture |
| Eggs | 8 large | Room temperature preferred |
| Whole milk | 2 cups | Or substitute with plant-based milk |
| Sharp cheddar cheese | 1 ½ cups, shredded | Or your favorite cheese |
| Baby spinach | 3 cups, chopped | Packed |
| Bell pepper | 1 cup, chopped | Red, yellow, or orange |
| Mushrooms | 1 cup, sliced | Optional, but adds umami flavor |
| Red onion | ½ cup, diced | Or use scallions for milder flavor |
| Garlic | 2 cloves, minced | Fresh is best |
| Salt | 1 teaspoon | Adjust to taste |
| Black pepper | ½ teaspoon | Freshly ground preferred |
| Olive oil | 1 tablespoon | For sautéing veggies |
Equipment
- 9×13-inch baking dish
- Large mixing bowl
- Whisk
- Cutting board and knife
- Skillet
- Spatula or wooden spoon
- Plastic wrap or foil
- Measuring cups and spoons
Instructions
-
Prepare the bread:
Cube the bread into roughly 1-inch pieces. If your bread is fresh, you can dry it out by baking the cubes on a sheet pan at 300°F (150°C) for 10 minutes.
Set aside.
-
Sauté the vegetables:
Heat the olive oil in a skillet over medium heat. Add the onion and cook for 2-3 minutes until softened.
Stir in the garlic, bell pepper, and mushrooms. Cook for another 4-5 minutes until vegetables are tender and any liquid has evaporated.
Add the chopped spinach and cook until just wilted. Remove from heat.
-
Assemble the casserole:
Grease your 9×13-inch baking dish. Spread the bread cubes evenly in the dish.
Top with the sautéed vegetable mixture and sprinkle the shredded cheddar cheese over everything.
-
Mix the custard:
In a large bowl, whisk together the eggs, milk, salt, and black pepper until well combined.
-
Pour the custard:
Slowly pour the egg mixture over the bread, vegetables, and cheese, ensuring everything is evenly moistened. Gently press down with a spatula to help the bread absorb the liquid.
-
Cover and refrigerate overnight:
Cover the baking dish tightly with plastic wrap or foil. Refrigerate for at least 8 hours, or overnight, to allow the flavors to meld and the bread to soak up the custard.
-
Bake:
In the morning, preheat your oven to 350°F (175°C). Remove the casserole from the refrigerator and let it sit at room temperature while the oven heats.
Uncover and bake for 45-55 minutes, or until the top is golden brown and the center is set. If the top is browning too quickly, tent loosely with foil.
-
Cool and serve:
Allow the casserole to cool for 10 minutes before slicing. Serve warm and enjoy!
Tips & Variations
-
Tip: If your casserole seems too dry in the morning, add a splash more milk before baking.
- Use different bread: Try sourdough, whole wheat, or gluten-free bread for unique flavors and textures.
- Add more veggies: Zucchini, broccoli, or sun-dried tomatoes all work beautifully.
- Switch up the cheese: Feta, Swiss, Monterey Jack, or gouda add their own delicious spin.
- Make it spicy: Add a pinch of red pepper flakes or diced jalapeño for heat.
- Vegan option: Use plant-based milk, vegan cheese, and an egg substitute like JUST Egg or a chickpea flour batter.
- Meal prep: Bake, cool, and cut into portions to reheat all week for fast, healthy breakfasts.
Nutrition Facts
| Nutrient | Per Serving (1/8 casserole) |
|---|---|
| Calories | 285 |
| Protein | 15g |
| Carbohydrates | 28g |
| Fat | 13g |
| Saturated Fat | 6g |
| Fiber | 3g |
| Sugar | 5g |
| Sodium | 520mg |
Note: Nutrition facts will vary based on ingredients and substitutions used.
Serving Suggestions
- With a fresh fruit salad: The light, sweet flavors are a perfect balance to the savory casserole.
- Top with avocado slices: For extra creaminess and healthy fats.
- Serve with hot sauce or salsa: Add a zesty kick.
- Pair with breakfast potatoes: Try our Crispy Breakfast Potatoes Recipe for a hearty brunch.
- Enjoy with a smoothie: Check out our Green Power Smoothie Recipe for a refreshing drink.
- Side of yogurt: A dollop of Greek yogurt or plant-based alternative adds creaminess and protein.
- For a brunch spread: Include our Fluffy Vegan Pancakes Recipe for the ultimate vegetarian brunch feast!
Conclusion
Waking up to a warm, comforting breakfast is one of life’s simple pleasures, and this Vegetarian Overnight Breakfast Casserole makes it effortless. With its blend of savory vegetables, creamy cheese, and fluffy eggs, it’s a crowd-pleaser that fits any occasion—from relaxed weekends to festive gatherings.
Plus, it’s an excellent canvas for creativity, allowing you to tailor the ingredients to your preferences or what you have in the fridge.
Give yourself the gift of a delicious, stress-free morning. Whether you’re feeding a family, hosting friends, or simply want to meal prep for yourself, this casserole promises satisfaction every time.
Don’t forget to check out our other breakfast favorites like Crispy Breakfast Potatoes, Green Power Smoothie, and Fluffy Vegan Pancakes to round out your morning menu. Enjoy your nourishing, delicious start to the day!
📖 Recipe Card: Vegetarian Overnight Breakfast Casserole
Description: This easy vegetarian breakfast casserole is prepared the night before and baked in the morning for a delicious, hearty meal. Perfect for busy mornings or special occasions.
Prep Time: PT20M
Cook Time: PT50M
Total Time: PT1H10M
Servings: 6 servings
Ingredients
- 8 large eggs
- 2 cups milk
- 1 teaspoon salt
- 1/2 teaspoon black pepper
- 4 cups cubed whole grain bread
- 1 cup shredded cheddar cheese
- 1 cup baby spinach, chopped
- 1 red bell pepper, diced
- 1 cup mushrooms, sliced
- 1/2 cup onion, diced
- 2 tablespoons olive oil
Instructions
- Grease a 9×13-inch baking dish with olive oil.
- In a skillet, sauté onion, bell pepper, and mushrooms in olive oil until softened.
- Add chopped spinach and cook until wilted, then remove from heat.
- Layer cubed bread evenly in the prepared baking dish.
- Spread the sautéed vegetables over the bread.
- Sprinkle shredded cheddar cheese on top.
- In a large bowl, whisk together eggs, milk, salt, and pepper.
- Pour egg mixture evenly over the casserole.
- Cover and refrigerate overnight.
- Preheat oven to 350°F (175°C) in the morning.
- Uncover and bake casserole for 45-50 minutes, or until set and golden.
- Let cool slightly before serving.
Nutrition: Calories: 270 kcal | Protein: 15 g | Fat: 13 g | Carbs: 22 g
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