Easy Vegetarian Breakfast Casserole
shared by Nibblore Kitchen
This make-ahead egg and vegetable breakfast casserole layers tender potatoes, colorful vegetables, cheddar, and fluffy seasoned eggs. Assemble it the night before for an easy brunch centerpiece, then bake it straight from the refrigerator. Briefly cooking the vegetables first prevents a watery casserole and concentrates their flavor. • Dry vegetables are essential: continue sautéing until no visible liquid remains in the skillet. • Shred cheddar from a block for smoother melting and a creamier texture. • For neat slices, let the casserole rest for the full 10 minutes before cutting. • Replace the cremini mushrooms with an equal weight of chopped zucchini, cooking until its released moisture evaporates. • Use Monterey Jack or low-moisture mozzarella in place of the cheddar. • Substitute an equal volume of unsweetened dairy-free milk for the whole milk and use a dairy-free shredded cheese if needed. Refrigerate cooled leftovers in an airtight container for up to 4 days, or freeze individual portions for up to 2 months. Thaw frozen portions overnight in the refrigerator. Reheat covered in a 325°F oven until the center reaches 165°F, about 15 minutes from refrigerated, or microwave individual portions in 45-second intervals until hot.
- Total time
- 80 min
- Servings
- 8
- Difficulty
- Beginner-friendly
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Save recipeIngredients
- 1 tbspolive oil, plus more for greasing
- 12 ozYukon Gold potatoes, cut into 1/2-inch cubes
- 1 mediumred bell pepper, cut into 1/2-inch pieces
- 1 smallyellow onion, diced
- 8 ozcremini mushrooms, sliced
- 2 cuppacked baby spinach, roughly chopped
- 12large eggs
- 1 cupwhole milk
- 1 tspkosher salt, divided
- ½ tspgarlic powder
- ½ tspsmoked paprika
- ¼ tspground black pepper
- 6 ozsharp cheddar cheese, shredded and divided
- 2 tbspthinly sliced chives
Instructions
- 1Lightly coat a 9-by-13-inch baking dish with olive oil. Place the cubed potatoes in a microwave-safe bowl with 2 tablespoons water, cover loosely, and microwave on high for 5 minutes. Drain thoroughly; the potatoes should be slightly tender at the edges but still firm in the center.
- 2Heat 1 tablespoon olive oil in a 12-inch skillet over medium-high heat. Add the potatoes and cook for 5 minutes, stirring once or twice, until lightly golden. Transfer them to the prepared baking dish.
- 3Add the bell pepper, onion, mushrooms, and 1/2 teaspoon salt to the same skillet. Cook over medium-high heat for 7 to 9 minutes, stirring occasionally, until the mushrooms release their liquid and the pan is nearly dry. Add the spinach and cook for 1 to 2 minutes, until wilted. Spread the vegetables evenly over the potatoes and let cool for 10 minutes.
- 4Whisk the eggs, milk, remaining 1/2 teaspoon salt, garlic powder, smoked paprika, and black pepper in a large bowl until no streaks of egg white remain. Stir in 4 ounces of the cheddar and the chives.
- 5Pour the egg mixture evenly over the cooled vegetables. Sprinkle the remaining 2 ounces cheddar on top. Cover tightly and refrigerate for at least 2 hours or up to 18 hours.
- 6When ready to bake, heat the oven to 350°F with a rack in the center. Remove the casserole from the refrigerator and uncover it while the oven heats, allowing it to stand at room temperature for 20 minutes.
- 7Bake uncovered for 40 to 45 minutes, rotating the dish after 25 minutes, until the edges are puffed, the center no longer looks wet, and an instant-read thermometer inserted in the center registers at least 160°F. If the cheese browns too quickly, loosely cover the dish with foil.
- 8Rest the casserole for 10 minutes so the egg custard can set. Cut into 8 portions and serve warm.