Description

This Everything Bagel Breakfast Casserole is a savory, cheesy baked dish perfect for brunch or a hearty breakfast. Featuring torn bagel pieces, Gruyere and Boursin cheeses, eggs, and optional plant-based sausage, it’s infused with the distinctive flavors of everything bagel seasoning and a touch of mustard and cayenne for a subtle kick. Ideal for make-ahead meals, it delivers a golden, flavorful, and comforting casserole.

Ingredients

Scale

Base Ingredients

2 large bagels, torn into 1 1/2-inch segments
8 eggs
2 cups milk, oat milk, or other plant-based milk
1 1/2 tablespoons Dijon-style mustard
1/4 teaspoon cayenne powder
1/2 teaspoon fine grain sea salt

Cheese

1 1/2 cups Gruyere cheese, grated
4 ounces Boursin cheese, feta, goat cheese, or cream cheese (choose one)

Additional Ingredients

a splash of extra virgin olive oil
6–8 ounces plant-based sausage (optional)
3 tablespoons everything bagel seasoning

Instructions

Preheat Oven and Prepare Dish: Preheat your oven to 350°F (175°C) and place a rack in the center. Lightly oil a 9×13-inch baking dish or a similarly sized equivalent to prevent sticking.
Cook Plant-Based Sausage (Optional): If using plant-based sausage, cook it in a small amount of extra virgin olive oil according to package instructions until browned on both sides. Remove the sausage from the skillet and place it on paper towels to cool slightly, then crumble it into pieces and set aside.
Mix Egg Mixture: In a large bowl, whisk together the Dijon mustard, cayenne powder, sea salt, milk (or plant-based milk), and eggs until fully blended and smooth.
Add Cheese, Bagels, and Sausage: To the egg mixture, add half of the grated Gruyere cheese, the bagel segments, and the crumbled cooked plant-based sausage (if using). Toss everything gently until the bagels and sausage are well coated with the egg mixture.
Assemble Casserole: Pour the mixture into the prepared baking dish. Evenly sprinkle the remaining Gruyere cheese over the top. Dot the casserole with crumbled pieces of Boursin cheese (or your chosen cheese alternative).
Refrigerate or Bake: At this point, you can cover and refrigerate the casserole overnight for convenience or proceed to bake right away.
Apply Seasoning and Bake: When ready to bake, sprinkle the casserole evenly with everything bagel seasoning. Cover the dish with foil, and poke a few holes in the foil to allow steam to escape. Bake covered for 45 minutes.
Finish Baking Uncovered: Carefully remove the foil and continue baking for an additional 30-40 minutes, or longer if baking straight from the refrigerator, until the casserole is beautifully golden and set.
Rest and Serve: Let the casserole cool for 5-10 minutes before serving to allow it to set and make slicing easier.

Notes

This casserole can be refrigerated overnight before baking, making it a great make-ahead dish.
You can use any bagel flavor, but everything bagels complement the seasoning best.
The plant-based sausage is optional but adds extra protein and flavor.
Feel free to substitute the Boursin cheese with feta, goat cheese, or cream cheese based on your preferences.
Make sure to poke holes in the foil when baking covered to prevent sogginess.
Allow the casserole to rest after baking for better texture and easier cutting.

Prep Time: 15 minutes
Cook Time: 1 hour 15 minutes
Category: Breakfast Casserole
Method: Baking
Cuisine: American

Keywords: everything bagel breakfast casserole, plant-based breakfast casserole, cheesy breakfast bake, make-ahead breakfast, vegetarian breakfast casserole