This potato and vegetable breakfast casserole combines cubed potatoes, sautéed bell peppers, spinach, and 12 eggs in one hearty dish designed to feed a crowd and prepared ahead for convenience.
*Service fees apply. Instacart® and the Instacart logo are registered trademarks of Maplebear Inc. d/b/a Instacart.
Instructions
1
Preheat the oven to 425°F and line a large rimmed baking sheet with parchment paper.
2
Place the potatoes on the prepared baking sheet and drizzle with 2 tablespoons of the olive oil. Season generously with salt and pepper and toss. Roast for 20 to 25 minutes, or until tender and browned.
3
Meanwhile, heat the remaining 1 tablespoon olive oil in a large skillet over medium heat. Add the onion and a pinch of salt and cook, stirring occasionally, for 5 minutes, or until soft.
4
Add the bell peppers and garlic and cook for 2 minutes.
5
Add the spinach and half of the green onions and cook until the spinach is just wilted. Season with salt and pepper and set aside.
6
In a large bowl, whisk together the eggs, milk, and ¼ teaspoon salt.
7
Reduce the oven temperature to 350°F. Lightly oil a 9×13-inch baking dish.
8
Spread the roasted potatoes in the prepared baking dish. Top with ¾ cup of the cheddar cheese, then the sautéed vegetables.
9
Pour the egg mixture over the vegetables and top with the remaining ½ cup cheddar cheese and remaining green onions.
10
Bake for 40 to 45 minutes, or until the eggs are set. Let stand for 5 minutes before slicing and serving.
Was this recipe helpful?
Tips & Notes
Pro tips
Cut potatoes into uniform ¼-inch cubes so they cook evenly; smaller pieces ensure tender potatoes throughout.
Sauté the potatoes, onions, and peppers in olive oil until the potatoes begin to soften before adding to the egg mixture—this prevents undercooked vegetables.
Squeeze excess moisture from spinach after thawing (if using frozen) to prevent a watery casserole.
Let the assembled casserole sit at room temperature for 15 minutes before baking for more even cooking.
Substitutions
Red bell pepper → orange or green bell pepper (same volume, slightly different flavor profile)
Baby spinach → kale or Swiss chard (massage or blanch briefly if using tougher greens)
Extra-virgin olive oil → butter or neutral oil (olive oil provides the best flavor here)
Small potatoes → russet potatoes (peel if preferred; cut slightly smaller since russets are larger)
Storage & make-ahead
Cover and refrigerate cooked casserole up to 4 days. Reheat in a 350°F oven, covered, for 15–20 minutes until heated through.
Equipment
9×13-inch baking dish · large skillet
Common Questions
Can I make this casserole the night before?
Yes. Assemble the casserole completely, cover, and refrigerate up to 24 hours. Bake from cold, adding 10–15 minutes to the cooking time.
What size baking dish do I need?
Use a 9×13-inch baking dish to accommodate all ingredients evenly.
Can I substitute the vegetables?
Yes. Swap bell peppers for zucchini or mushrooms, and spinach for kale or broccoli in equal amounts.
How do I know when the casserole is done?
It's ready when the eggs are set and a knife inserted in the center comes out clean, typically 35–45 minutes at 350°F.
Can I freeze leftovers?
Yes. Cool completely, cut into portions, wrap in plastic wrap and foil, and freeze up to 3 months. Reheat in a 350°F oven until warmed through.