A fluffy vegetarian breakfast casserole with eggs, cheese, peppers, and potatoes, 100% meatless and made ahead. ♡

This vegetarian breakfast casserole is the make ahead brunch that wins every holiday morning. Fluffy scrambled eggs, tender roasted potatoes, sauteed peppers, and gooey cheddar baked into a golden casserole you can prep the night before. For more ideas, see our Vegetarian Enchiladas.

100% meatless and feeds a crowd without trying. One dish brunch that tastes like a diner breakfast plate. Let’s make it together.

Ingredients

Vegetarian Breakfast Casserole

1.5 lbs russet potatoes, peeled and cubed
3 tbsp olive oil, divided
1 medium yellow onion, diced
1 red bell pepper, diced
2 cloves garlic, minced
10 large eggs
1.5 cups half and half
2 cups shredded cheddar
1 cup shredded mozzarella
4 slices day old bread, cubed, optional
2 tbsp fresh chives, chopped
1 tsp dried thyme
salt and pepper, to taste

How to Make Vegetarian Breakfast Casserole

**Roast potatoes.** Heat oven to 425F. Toss potato cubes with 2 tbsp oil, salt, and pepper. Roast 20 minutes, stirring halfway, until golden.
**Saute veg.** Heat remaining oil in a skillet. Cook onion and bell pepper 5 minutes. Add garlic, cook 30 seconds.
**Whisk.** Whisk eggs, half and half, thyme, salt, and pepper in a large bowl.
**Assemble.** Reduce oven to 350F. Grease a 9×13 baking dish. Spread bread cubes, then roasted potatoes, then sauteed veg, then 1.5 cups cheese. Pour the egg mixture over. Top with remaining cheese.
**Bake.** Bake uncovered 40 to 45 minutes until set in the center and golden on top.
**Rest.** Rest 10 minutes. Top with fresh chives. Slice and serve.

Why This Recipe Works

Whisking the eggs with half and half (not milk) is the key to a breakfast casserole that stays fluffy and custardy, not rubbery. The extra fat in half and half keeps the eggs tender and delivers a luxurious mouthfeel. Using milk alone makes a drier, more scrambled texture.

Roasting the potatoes for 20 minutes before adding them to the casserole is the step that transforms this from a sad soggy bake into something you actually crave. Raw potatoes never cook through in an egg casserole. Pre roasted potatoes give you crispy edges and creamy centers in every bite.

Assembling the casserole the night before and letting it rest in the fridge is the make ahead magic. As it sits, the bread soaks up the egg mixture into a savory custard, the flavors meld, and the whole thing bakes into a cohesive slice. A same day casserole has dry spots and uneven texture. For more ideas, see our Vegetarian Stuffed Shells.

Tips

Use half and half for the fluffiest custard. Milk alone makes drier casserole.
Vegan swap: use 1 block silken tofu blended smooth plus plant milk instead of eggs and dairy.
Store leftovers in the fridge for up to 4 days.
Reheat covered in a 350F oven for 15 minutes. Microwave in 90 second bursts.
Assemble the night before. The flavors meld and the texture improves overnight.
Use day old bread. Fresh bread turns gummy in an egg casserole.

Variations

Add sauteed spinach or kale for extra greens.
Swap cheddar for Gruyere or Swiss for a sharper flavor.
Add sundried tomatoes for a Mediterranean spin.
Top with sliced avocado after baking for a California vibe.
Make it vegan with a silken tofu scramble base and vegan cheese.
Use sweet potatoes instead of russet for a sweeter, more colorful casserole.

Looking for more vegetarian ideas? Try our Vegetarian Chili or Vegetarian Lasagna next.

Common Mistakes to Avoid

Raw potatoes: Always pre roast potatoes. Raw potatoes never cook through in an egg casserole.
Using milk only: Use half and half for custardy eggs. Milk makes rubbery casserole.
Fresh bread: Day old bread soaks up the custard properly. Fresh bread turns gummy.
Skipping the rest: Rest the baked casserole 10 minutes before slicing. Cutting hot means sloppy slices.

Vegetarian Breakfast Casserole

Vegetarian breakfast casserole with eggs, potatoes, and cheese. 100% meatless make ahead brunch.

Print Recipe Pin Recipe

Prep Time 15

Cook Time 55

Total Time 1 10

Servings: 8 servings

Course: Breakfast

Cuisine: American

Calories: 380

Ingredients Method Notes

Ingredients

1.5 lbs russet potatoes peeled and cubed
3 tbsp olive oil divided
1 medium yellow onion diced
1 red bell pepper diced
2 cloves garlic minced
10 large eggs
1.5 cups half and half
2 cups shredded cheddar
1 cup shredded mozzarella
4 slices day old bread cubed, optional
2 tbsp fresh chives chopped
1 tsp dried thyme
salt and pepper to taste

Method

**Roast potatoes.** Heat oven to 425F. Toss potato cubes with 2 tbsp oil, salt, and pepper. Roast 20 minutes, stirring halfway, until golden.
**Saute veg.** Heat remaining oil in a skillet. Cook onion and bell pepper 5 minutes. Add garlic, cook 30 seconds.
**Whisk.** Whisk eggs, half and half, thyme, salt, and pepper in a large bowl.
**Assemble.** Reduce oven to 350F. Grease a 9x13 baking dish. Spread bread cubes, then roasted potatoes, then sauteed veg, then 1.5 cups cheese. Pour the egg mixture over. Top with remaining cheese.
**Bake.** Bake uncovered 40 to 45 minutes until set in the center and golden on top.
**Rest.** Rest 10 minutes. Top with fresh chives. Slice and serve.

Notes

Use half and half for the fluffiest custard. Milk alone makes drier casserole. Vegan swap: use 1 block silken tofu blended smooth plus plant milk instead of eggs and dairy. Store leftovers in the fridge for up to 4 days.

Sources: USDA FoodData Central for nutrition data and Academy of Nutrition and Dietetics vegetarian guide.