This overnight vegetarian tater tot breakfast casserole will make your breakfast or brunch dreams come true. It's loaded with healthy veggies and flavored with smoked paprika and two kinds of cheese. You can prepare it the night before and bake it the next morning. It's the perfect holiday breakfast idea or great for brunch!

Vegetarian tater tot breakfast casserole with a serving taken out in a white ceramic baking dish.

This tasty overnight vegetarian tater tot breakfast casserole is just the thing you need when you’re looking to feed a crowd for breakfast or brunch but don’t want to put in a lot of effort the morning you serve it. It’s prepared the night before then you simply bake it the next morning! Of course, you could always prepare it the morning you plan on serving it and bake it right away. It’s a great holiday breakfast idea too!

We love overnight breakfast recipes around here – like this overnight sausage breakfast casserole or these dairy-free overnight oats.

What You’ll Love About This Recipe

Make-Ahead Convenience. The recipe can be assembled the night before and baked in the morning, making it perfect for a stress-free breakfast or brunch.
Perfect for Feeding a Crowd. The casserole serves multiple people, making it ideal for family breakfasts, brunch gatherings, or holiday mornings.
Hearty and Filling. This casserole is packed with vegetables, eggs, and cheese, making it a hearty and filling breakfast that will keep you satisfied well into the day.
Vegetarian-Friendly. It’s a delicious and satisfying option for vegetarians, featuring a variety of fresh vegetables and savory flavors.
Customizable. This recipe is easily adaptable – swap in your favorite veggies or cheeses, or add some spice with jalapeños or hot sauce.
Cheesy Goodness. The combination of cheddar and Monterey Jack cheeses gives the casserole a rich, melty texture that’s hard to resist.

Ingredients

Frozen Tater Tots.
Olive oil. This is used to sauté the mushrooms and onions.
Sweet onion. Diced.
Sliced cremini mushrooms. You can substitute your favorite mushroom variety.
Milk.
Heavy cream. For a lower fat version, you can substitute half and half or milk.
Salt. Salt enhances the flavor of this breakfast casserole. You can add more or less according to your taste.
Smoked paprika. We love the flavor that smoked paprika adds, but you can substitute regular paprika, or 1/4 teaspoon of cayenne pepper.
Large eggs. Beaten.
Small red bell pepper. Diced. Adds color and flavor.
Small green bell pepper. Diced. Adds color and flavor.
Cheddar cheese. Grated.
Monterey Jack cheese. Grated.
Salt and pepper. To taste.
Medium zucchini. Sliced. Adds nutrition and visual interest.
Chopped fresh basil. Used as a garnish. You can also garnish with micro greens, thyme, or parsley.

See recipe card for quantities.

Instructions

Frozen tater tots lined up in the bottom of a white ceramic baking dish. — Spray a 9 by 13 inch baking dish with cooking spray or rub with butter. Arrange the tater tots in the bottom of the dish.

**Note:** If you prefer a crispy top, add the filling, egg mixture, and veggies first then arrange the frozen tater tots on top.

Cooked sliced mushrooms in a stainless steel skillet. — Heat olive oil in a large skillet over medium high heat. Then add the mushrooms and stir and cook until mushrooms are browned, about 3 minutes. Remove mushrooms to a plate.

Cooked diced onion in a stainless steel skillet. — Add onion to hot skillet, lower heat to medium, and stir and cook until onions begin to turn translucent, about 6 minutes.

Tater tots and mushroom and onion mixture in a white ceramic baking dish. — Remove from heat and allow to cool for a minute or two, then sprinkle onions and mushrooms over the tater tots.

Eggs and cream mixture in a white ceramic bowl with a whisk. — In a large bowl, combine the milk, cream, salt, paprika, eggs, bell peppers, and half the cheeses.

Casserole mixture in a white ceramic baking dish. — Pour the mixture over the tots and mushroom mixture. Season with salt and pepper to taste.

Casserole mixture topped with zucchini slices in a white ceramic baking dish. — Arrange the zucchini slices over the top.

Casserole mixture topped with cheese in a white baking dish. — Top with remaining cheese.

Cover with foil and refrigerate overnight. Alternatively, you can bake it right away.

The next morning, preheat the oven to 350 F (177 C). Bake covered for about 25 minutes. Remove the foil and continue to bake until the cheese is brown and bubbly and the casserole is cooked through about another 25 to 35 minutes.

Allow to cool slightly then garnish with fresh basil or micro greens.

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Tools you’ll need

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Click here to learn how to make this breakfast casserole in a visual story.

Serving of vegetarian tater tot breakfast casserole in a small grey ceramic mug bowl

Variations

Spicy – Substitute cayenne pepper for the smoked paprika and add a diced jalapeño or two.
Meat lovers – Add cooked sausage, bacon, or ham. You can either leave the mushrooms or substitute them for your breakfast meat of choice. Add the cooked meat along with the cooked onions.

Tips

Crispy Top. If you prefer a crispy top, add the tater tots last during assembly. For an even crispier top, pre-bake the Tater Tots following the package instructions.
Drain Excess Moisture. When cooking the mushrooms and onions, make sure to cook off any excess moisture. This prevents the casserole from becoming soggy and helps keep the tater tots crispy.
Avoid Overcrowding the Pan. When sautéing the mushrooms and onions, don’t overcrowd the skillet. Cook them in batches if necessary to ensure they brown properly, adding more flavor to the casserole.
Bake Uncovered for Crispy Tops. To ensure the tater tots on top get crispy, bake the casserole uncovered for the last 25-35 minutes. This allows the heat to circulate and the cheese to brown and bubble.
Use a Hot Oven. Make sure your oven is fully preheated before placing the casserole inside.
Add Cheese in Two Layers. Add some cheese in the middle layer with the vegetables and egg mixture, and then top the casserole with the remaining cheese. This provides cheesy goodness throughout and a nice cheesy crust on top.
Let It Rest. After baking, let the casserole rest for 5-10 minutes before serving. This allows it to set, making it easier to slice and serve without falling apart.

Storage

Refrigerating Leftovers

Cool Completely. Allow the casserole to cool completely at room temperature before storing.
Transfer to an Airtight Container. Once cooled, transfer the leftovers to an airtight container. Alternatively, you can cover the casserole dish tightly with plastic wrap or aluminum foil.
Store in the Refrigerator. Place the container or covered dish in the refrigerator. The casserole will stay fresh for up to 3-4 days.

Freezing for Later

Cool Completely. Let the casserole cool completely before freezing.
Portion for Easy Reheating. For convenience, you can portion the casserole into individual servings and place them in airtight, freezer-safe containers or freezer bags. This makes reheating easier and quicker.
Wrap for Protection. If freezing the whole casserole, wrap the entire dish tightly with plastic wrap, followed by a layer of aluminum foil. This helps prevent freezer burn.
Label and Freeze. Label the container or dish with the date, then freeze. The casserole can be frozen for up to 2-3 months.

Reheating Instructions

From the Refrigerator:
- Microwave. Reheat individual portions in the microwave on medium heat for 1-2 minutes, or until heated through.
- Oven. Preheat your oven to 350 F (177 C). Cover the casserole with foil and bake for 15-20 minutes, or until heated through.
From the Freezer:
- Thaw First (Recommended). For best results, thaw the casserole in the refrigerator overnight before reheating. Then follow the reheating instructions above.
- Reheat from Frozen. If you’re short on time, you can reheat directly from frozen. Preheat the oven to 350 F (177 C), cover the casserole with foil, and bake for 25-30 minutes. Remove the foil and bake for an additional 10-15 minutes, or until heated through and the top is crispy.

Storing Unbaked Casserole:

Refrigerate Overnight. If you’ve prepped the casserole but haven’t baked it yet, you can cover it tightly and store it in the refrigerator overnight.
Freeze Before Baking. To freeze the unbaked casserole, wrap it tightly in plastic wrap and then foil, and store it in the freezer for up to 2 months. When ready to bake, thaw it in the refrigerator overnight and bake as directed, adding a few extra minutes if needed.

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Prep Time:30

Cook Time:1

Total Time:1 30

Equipment

Measuring spoons

Liquid measuring cups

Chef's knife

9 by 13 inch baking pan

Large skillet

Large bowl

Ingredients

1 32 oz. bag frozen Tater Tots™
1 tablespoon olive oil
1 medium sweet onion Diced.
2 cups sliced cremini mushrooms
¾ cup milk
¾ cup heavy cream
1 teaspoon salt Or to taste.
½ teaspoon smoked paprika
6 large eggs Beaten.
1 small red bell pepper Diced.
1 small green bell pepper Diced.
1½ cups cheddar cheese Grated.
1½ cups Monterey Jack cheese Grated.
salt and pepper To taste.
1 medium zucchini Sliced.
1 tablespoon chopped fresh basil

US Customary – Metric

Instructions

Spray a 9 by 13 inch baking dish with cooking spray or rub with butter. Arrange the tater tots in the bottom of the dish. See Note.
1 32 oz. bag frozen Tater Tots™
Heat olive oil in a large skillet over medium high heat. Then add the mushrooms and stir and cook until mushrooms are browned, about 3 minutes. Remove mushrooms to a plate.
1 tablespoon olive oil, 1 medium sweet onion, 2 cups sliced cremini mushrooms
Add onion to hot skillet, lower heat to medium, and stir and cook until onions begin to turn translucent, about 6 minutes.
Remove from heat and allow to cool for a minute or two, then sprinkle onions and mushrooms over the tater tots.
In a large bowl, combine the milk, cream, salt, paprika, eggs, bell peppers, and half the cheeses.
¾ cup milk, ¾ cup heavy cream, 1 teaspoon salt, ½ teaspoon smoked paprika, 6 large eggs, 1 small red bell pepper, 1 small green bell pepper, 1½ cups cheddar cheese, 1½ cups Monterey Jack cheese
Pour the mixture over the tots and mushroom mixture. Season with salt and pepper to taste. Arrange the zucchini slices over the top and top with remaining cheese.
1 medium zucchini, salt and pepper
Cover with foil and refrigerate overnight. Alternatively, you can bake it right away.
The next morning, preheat the oven to 350 F (177 C). Bake covered for about 25 minutes. Remove the foil and continue to bake until the cheese is brown and bubbly and the casserole is cooked through about another 25 to 35 minutes.
Allow to cool slightly then garnish with fresh basil.
1 tablespoon chopped fresh basil