Name: Easy Make-Ahead Breakfast Casserole Recipe
Prep time: 20 min
Cook time: 45 min
Total time: 1 h 5 min
Cuisine: American
Ingredients: 4 cups (175g or 6 oz) cubes of crusty bread; 1 teaspoon olive oil; 1 pound ground pork sausage, casings removed; 1 teaspoon dried rosemary or Italian seasoning (optional); 3/4 cup (100g) chopped yellow onion (1/2 of a large onion); 2 garlic cloves, minced; 2 cups (275g or 9-10 oz) chopped bell peppers; 1 cup (100g or 3 oz) sliced mushrooms; 1 cup roughly chopped fresh spinach; 12 large eggs; 1/4 teaspoon salt; 1/8 teaspoon freshly ground black pepper; 2/3 cup (160ml) milk or half-and-half; 1 cup (100g or 3.5 oz) shredded cheddar cheese; Green onion and/or chopped parsley

Ingredients

4 cups (175g or 6 oz) cubes of crusty bread*

1 teaspoon olive oil

1 pound ground pork sausage, casings removed*

1 teaspoon dried rosemary or Italian seasoning, optional

3/4 cup (100g) chopped yellow onion (1/2 of a large onion)

2 garlic cloves, minced

2 cups (275g or 9-10 oz) chopped bell peppers

1 cup (100g or 3 oz) sliced mushrooms

1 cup roughly chopped fresh spinach

12 large eggs

1/4 teaspoon salt

1/8 teaspoon freshly ground black pepper

2/3 cup (160ml) milk or half-and-half*

1 cup (100g or 3.5 oz) shredded cheddar cheese

Optional garnish: green onion and/or chopped parsley

Instructions

Step 1: Grease a 9×13-inch or any 3–4-quart oven-safe dish. Arrange the bread cubes in an even layer at the bottom of the pan.

Step 2: Heat olive oil in a large skillet over medium heat. Add the ground sausage and rosemary or Italian seasoning, if using. Break up the sausage into bite-size pieces as it cooks.

Step 3: Add the chopped onion, minced garlic, bell peppers, mushrooms, and spinach to the skillet. Cook until the vegetables soften slightly and the sausage is mostly cooked through, about 5–6 minutes.

Step 4: Remove the sausage and vegetable mixture from heat and spread it in an even layer over the bread cubes in the baking dish.

Step 5: In a large bowl, whisk together the eggs, salt, pepper, milk or half-and-half, and shredded cheddar cheese. Pour this mixture evenly over the sausage and vegetables. Sprinkle a little extra salt and pepper on top.

Step 6: Cover the casserole with plastic wrap or aluminum foil and refrigerate for at least 30 minutes or up to 24 hours. When ready to bake, let it sit at room temperature for 10–15 minutes while preheating the oven.

Step 7: Preheat the oven to 375°F (191°C). Bake the casserole uncovered until the top is golden, edges are crisp, and a toothpick inserted in the center comes out clean—about 40–45 minutes.

Step 8: Let the casserole cool for 10 minutes before slicing. Garnish with green onions or parsley if desired, then serve.

Tips & Variations

Use day-old crusty bread for better texture, or substitute with whole wheat or sourdough for variation.

Try swapping pork sausage with turkey sausage or cooked bacon for a different flavor.

Add other vegetables like zucchini or kale to customize the veggie mix.

For a vegetarian version, omit the sausage and add extra mushrooms and spinach.

Use a mix of cheeses, such as mozzarella or pepper jack, for a unique taste.

FAQs

Can I prepare this casserole completely ahead of time?

Yes, you can assemble the casserole up to 24 hours before baking. Keep it covered and refrigerated, then bake it directly from the fridge, allowing it to come to room temperature first.

Can I make this casserole dairy-free?

Absolutely! Use dairy-free milk alternatives such as almond or oat milk, and substitute the cheddar cheese with a dairy-free cheese or omit it entirely.