Form K Strata BC: Easy Breakfast Casserole

Form K Strata BC is a savory bread-and-egg casserole that’s a staple for weekend brunches and holiday mornings. It layers torn bread, cheese, vegetables, and sometimes meat, all bound together with a rich custard of eggs and milk. Because it’s assembled ahead and baked until puffed and golden, it’s a forgiving dish that feeds a crowd with minimal morning fuss.

Ingredients

1 lb (450 g) day-old rustic bread (like sourdough or French loaf), cut into 1-inch cubes (about 10 cups)
2 tbsp (30 g) unsalted butter, melted, plus more for greasing
8 large eggs
2 cups (480 ml) whole milk
1 cup (240 ml) heavy cream
1 tsp Dijon mustard
1 tsp kosher salt
½ tsp black pepper
¼ tsp freshly grated nutmeg
2 cups (200 g) shredded sharp cheddar cheese, divided
1 cup (100 g) shredded Gruyère or Swiss cheese
1 medium leek (about 150 g), white and light green parts only, thinly sliced
1 cup (150 g) frozen peas, thawed
8 oz (225 g) cooked ham, diced (optional)

Instructions

Grease a 9×13-inch (23×33 cm) baking dish with butter. Spread the bread cubes in the dish and drizzle with the melted butter. Toss gently to coat.
In a large bowl, whisk together the eggs, milk, cream, Dijon mustard, salt, pepper, and nutmeg until fully combined.
Stir in 1½ cups (150 g) of the cheddar, the Gruyère, leek, peas, and ham (if using).
Pour the egg mixture over the bread cubes. Press down lightly with a spatula to ensure all bread is soaked. Sprinkle the remaining ½ cup (50 g) cheddar on top.
Cover the dish with plastic wrap or foil and refrigerate for at least 30 minutes, or up to 24 hours. (If chilling overnight, let sit at room temperature for 20 minutes before baking.)
Preheat the oven to 350°F (175°C).
Bake, uncovered, for 50–55 minutes, until the top is golden brown and a knife inserted in the center comes out clean. The internal temperature of the egg custard should reach 160°F (71°C) as the safe minimum per USDA FSIS.
Let rest for 10 minutes before slicing and serving warm.

Tips

Bread choice: Stale or day-old bread works best because it soaks up the custard without turning mushy. If your bread is fresh, toast the cubes in a 300°F (150°C) oven for 10 minutes to dry them out.
Don’t over-soak: If you refrigerate longer than 24 hours, the bread can break down. Stick to the 30-minute minimum or overnight max.
Check doneness: The center should be set but still slightly jiggly when you shake the dish; it will finish setting as it rests. Use a thermometer to be sure.
Substitutions: Swap the leek for 1 cup chopped onion or shallot; use any melting cheese like Monterey Jack or fontina. For a vegetarian version, omit the ham and add 1 cup sautéed mushrooms.

Serving Suggestions

Serve this strata warm, straight from the dish, with a simple green salad dressed in lemon vinaigrette for lunch, or alongside roasted potatoes and fresh fruit for brunch. A dollop of crème fraîche or hot sauce on top is a nice touch.

Variations

Mediterranean: Replace ham with ½ cup sun-dried tomatoes, ½ cup crumbled feta, and 2 cups baby spinach.
Southwest: Use pepper Jack cheese, add 1 can (4 oz / 115 g) diced green chiles, and swap peas for corn.
Herb and mushroom: Sauté 8 oz (225 g) sliced mushrooms with 2 cloves garlic, and add 2 tbsp chopped fresh thyme or rosemary.

Storage and Reheating

Refrigerate leftovers in an airtight container for up to 4 days. To reheat, place a portion 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 covered with foil to prevent drying. You can also freeze the baked strata for up to 2 months; thaw overnight in the fridge and reheat as above.

Frequently Asked Questions

Can I make this strata ahead of time? Yes, that’s the beauty of it. Assemble the dish, cover, and refrigerate for up to 24 hours before baking. Add about 10 minutes to the bake time if starting from cold.

Why is my strata soggy? Sogginess usually happens if you use fresh bread that absorbs too much liquid or if you over-soak. Use stale bread and don’t let it sit longer than 24 hours. Also, make sure to bake until the center is set, not just the edges.

Can I use half-and-half instead of heavy cream? Yes, replace the cream with an equal amount of half-and-half or even whole milk. The strata will be slightly less rich and may need a minute or two less baking time.

Can I freeze the unbaked strata? It’s better to bake first, then freeze. Unbaked strata can become watery when thawed because the custard separates. If you must freeze unbaked, do so for no more than 1 month and thaw in the fridge overnight before baking.

What if I don’t have leeks? Use 1 cup of finely chopped yellow onion or shallots. Sauté them in a little butter until soft before adding to the egg mixture to mellow their flavor.

Is this gluten-free? Not as written, but you can use gluten-free bread and ensure your Dijon mustard is gluten-free. The rest of the ingredients are naturally gluten-free.

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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