Work Strata Group Limited: Easy Make-Ahead Breakfast Casserole

Work Strata Group Limited is a hearty, make-ahead breakfast casserole that layers bread, eggs, cheese, and vegetables into a custard-like bake. It’s a practical dish for feeding a crowd or prepping busy mornings, and it comes together with simple ingredients you can vary by what you have on hand. The name nods to its “work group” versatility—it’s a reliable, no-fuss meal that works for brunch, lunch, or dinner.

Ingredients

8 cups (about 240 g) day-old bread, cut into 1-inch cubes (French, sourdough, or whole wheat)
2 cups (200 g) shredded sharp cheddar cheese, divided
1 cup (100 g) shredded Gruyère or Swiss cheese
1 medium onion, diced (about 1 cup / 150 g)
1 red bell pepper, diced (about 1 cup / 150 g)
2 cups (150 g) sliced mushrooms
2 cups (60 g) fresh spinach, roughly chopped
8 large eggs
2 cups (480 ml) whole milk
1 teaspoon Dijon mustard
1 teaspoon salt
½ teaspoon black pepper
¼ teaspoon ground nutmeg (optional)
2 tablespoons olive oil

Instructions

Heat the olive oil in a large skillet over medium heat. Add the onion, bell pepper, and mushrooms. Cook, stirring occasionally, until softened and lightly browned, about 8–10 minutes. Add the spinach and cook until wilted, about 2 minutes more. Remove from heat and let cool slightly.
In a large bowl, whisk together the eggs, milk, Dijon mustard, salt, black pepper, and nutmeg (if using) until well combined.
Spread the bread cubes evenly in a 9×13-inch (23×33 cm) baking dish. Scatter the cooked vegetable mixture over the bread. Sprinkle with 1½ cups of the cheddar and all of the Gruyère. Pour the egg mixture evenly over everything, pressing down gently with a spatula to help the bread absorb the liquid. Sprinkle the remaining ½ cup cheddar on top.
Cover the dish with foil and refrigerate for at least 30 minutes, or up to overnight (see Tips).
When ready to bake, preheat the oven to 350°F (175°C). Remove the dish from the fridge while the oven heats.
Bake covered for 30 minutes. Uncover and bake for another 20–25 minutes, until the top is golden brown and the center is set (a knife inserted near the middle comes out clean). The internal temperature of the egg mixture should reach 160°F (71°C), the USDA FSIS safe minimum for egg dishes.
Let rest for 5–10 minutes before slicing and serving.

Tips

Bread choice: Stale or day-old bread works best because it soaks up the custard without turning mushy. If using fresh bread, toast the cubes lightly in the oven for 5 minutes at 350°F (175°C) before assembling.
Make-ahead: Assemble the strata, cover, and refrigerate for up to 24 hours before baking. This allows the flavors to meld and the bread to absorb the custard fully. If baking straight from the fridge, add 5–10 minutes to the covered baking time.
Substitutions: Swap the mushrooms for zucchini, the spinach for kale, or the Gruyère for extra cheddar. Use half-and-half instead of milk for a richer custard.
Common mistake: Overbaking dries out the strata. Check at the lower end of the time range; the center should be just set, not jiggly.

Serving Suggestions

Serve warm slices with a simple green salad dressed with lemon vinaigrette, or with roasted tomatoes and a side of fresh fruit. It’s also excellent with a dollop of sour cream or hot sauce. For brunch, pair with mimosas or coffee.

Variations

Meat lover’s: Add 1 cup (150 g) cooked, crumbled breakfast sausage or diced ham along with the vegetables.
Herb and tomato: Fold in ¼ cup fresh basil and 1 cup halved cherry tomatoes just before pouring the custard.
Southwest: Replace the spinach with 1 cup corn kernels and 1 diced jalapeño, and use pepper jack cheese instead of Gruyère.

Storage and Reheating

Refrigerate leftovers in an airtight container for up to 4 days. To reheat, place a slice on a microwave-safe plate and heat in 30-second bursts until warmed through, or reheat in a 350°F (175°C) oven for 10–15 minutes. The strata also freezes well after baking: wrap individual slices in plastic wrap and freeze for up to 2 months. Thaw overnight in the fridge before reheating.

Frequently Asked Questions

Can I use gluten-free bread? Yes, choose a sturdy gluten-free bread (like sourdough-style) and toast it lightly before assembling. Gluten-free bread can get gummy if too moist, so toasting helps.

Do I have to refrigerate before baking? No, but it’s recommended. Chilling lets the bread absorb the custard, giving a softer, more cohesive texture. If you skip it, bake covered for 35 minutes and then uncovered for 20–25 minutes.

Can I make this without eggs? You can try a vegan egg substitute, but the texture will be different. For a custard-like result, use a commercial egg replacer or a mixture of silken tofu blended with non-dairy milk. The bake time may vary.

Why is my strata watery? This usually happens if the vegetables release too much liquid. Make sure to cook the mushrooms until browned and the spinach until wilted, and drain any excess liquid before adding to the dish.

Can I use low-fat milk? Yes, but the custard will be less rich. Whole milk or a combination of milk and cream gives the best texture.

How do I know it’s fully cooked? The center should be set and not jiggle when you shake the dish. A food thermometer inserted into the middle should read 160°F (71°C).

More recipes to cook

Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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