Why This Recipe Works

Overnight Magic: Assemble everything the evening before; the bread soaks up the seasoned custard so flavors meld while you sleep.
Cheese on Cheese: A duo of sharp white cheddar for bite and young Gouda for stretch gives you the best melt.
Texture Contrast: Cubed sourdough stays custardy inside while the corn-flake topping bakes up audibly crisp.
Feed-a-Crowd Size: One 13×9-inch pan yields twelve hearty squares—perfect for buffet-style brunch.
Flexible Mix-ins: Fold in sautéed spinach, roasted peppers, or leftover ham without changing bake time.
Freezer-Friendly: Bake, cool, slice, and freeze individual portions; reheat in the toaster oven for 10 minutes.
Beginner-Proof: No béchamel, no separate egg-white whipping—just whisk, pour, and bake.

Ingredients You'll Need

Great casserole starts with great building blocks. Buy a bakery loaf of sourdough or country white that’s already a day old; slightly stale bread soaks up the custard without turning gummy. If yours is fresh, cube it and leave it uncovered on a sheet pan for two hours to dry out. For the cheese, avoid pre-shredded bags—they’re dusted with cellulose that inhibits smooth melting. Grate a 10-oz block of sharp white cheddar and a 6-oz piece of Gouda yourself; the five extra minutes translate into miles of cheese pull. Whole milk keeps the interior lush, but you can swap in 2% or a 50-50 blend of milk and half-and-half for richer company. Dijon mustard, hot sauce, and Worcestershire may seem minor, yet they bloom in the background and make guests ask, “Why does this taste so good?” Buy good eggs—pasture-raised if possible—for golden yolks that tint the custard sunrise-orange. Finally, don’t skip the corn-flake topping. Crushed corn flakes tossed with melted butter deliver the crackly crunch that balances the cheesy softness underneath.

How to Make Cheesy Breakfast Casserole for New Year Day Brunch

Prep Your Pan & Bread

Butter a 13×9-inch glass or ceramic baking dish. Cut sourdough into 1-inch cubes (about 12 cups). Spread cubes in the dish; set aside while you mix the custard so the bread begins to stale slightly more.

Whisk the Custard

In a large bowl whisk 10 large eggs until homogenous. Whisk in 3 cups whole milk, 2 Tbsp Dijon mustard, 1 Tbsp Worcestershire, 1 tsp kosher salt, ½ tsp black pepper, ¼ tsp hot sauce, and ¼ tsp freshly grated nutmeg. The mixture should taste slightly over-seasoned; it will mellow once baked.

Add the Cheeses

Reserve 1 cup (about 3 oz) of the grated cheddar for topping. Stir remaining cheddar and all the Gouda into the custard until the shreds are separated and coated. This prevents cheese clumps in the final bake.

Pour & Press

Ladle the cheesy custard evenly over the bread cubes. Use a spatula to press bread down gently so every cube is moistened. Scatter reserved cheddar across the surface. Cover the dish with foil and refrigerate at least 4 hours or up to 24 hours.

Make the Crunch Lid

In a small bowl, toss 2 cups lightly crushed corn flakes with 3 Tbsp melted unsalted butter until evenly coated. Store in a zip-top bag at room temperature so it stays crisp.

Bake Low & Slow

The next morning, preheat oven to 325°F (163°C). Let the casserole stand at room temp while oven heats. Bake foil-on for 35 minutes to set the custard, then remove foil, sprinkle corn-flake mixture evenly on top, and bake 20–25 minutes more until puffed, golden, and an instant-read thermometer inserted in the center registers 195°F (90°C).

Rest & Serve

Cool 10 minutes before slicing; this sets the custard and prevents a molten cheese river. Cut into 12 generous squares and serve with fresh fruit or a citrusy salad to balance the richness.

Expert Tips

Temperature Is Truth

An instant-read thermometer eliminates guesswork. Anything above 200°F yields dry curds; anything under 190°F leaks when cut.

Midnight Assembly

If you’re coming home late, build the casserole, press plastic wrap directly onto the surface, and pop it into the fridge. Top with corn flakes only before baking.

Prevent Sog

If your sourdough is very fresh and soft, toast cubes at 300°F for 10 minutes to dry them slightly before assembly.

Clean Slices

Use a serrated knife dipped in hot water then wiped dry for picture-perfect squares that don’t drag the topping off.

Doubling Duty

For two pans, stagger oven racks and rotate halfway through. Bake time increases by only 5–7 minutes.

Individual Muffin Version

Divide the soaked bread among greased muffin cups, top with corn flakes, and bake 18–20 minutes for grab-and-go portions.

Variations to Try

Storage Tips

Make-Ahead: The unbaked casserole keeps 24 hours refrigerated. Beyond that, the bread can break down, so freeze instead. Wrap the unbaked dish (minus corn flakes) in a layer of plastic and then foil; freeze up to 2 months. Thaw 24 hours in the refrigerator, add topping, and bake as directed.

Leftovers: Cool completely, cut into squares, and refrigerate in an airtight container up to 4 days. Reheat single portions in the microwave 45–60 seconds or in a 300°F toaster oven 8–10 minutes to restore crunch. For longer storage, wrap each square in plastic and freeze up to 2 months. Thaw overnight in the fridge or microwave from frozen 90 seconds, then toast briefly.

Frequently Asked Questions

Yes. Challah, brioche, or a sturdy whole-grain loaf work, but avoid very soft sandwich bread which can turn mushy. Aim for 10–11 oz weight after cubing.

Vegetables with high water content (fresh tomatoes, raw zucchini) can weep. If adding them, sauté and cool first. Also verify your oven temperature with an oven thermometer; under-baking leaves unset custard that releases moisture when cut.

Absolutely. Halve all ingredients and bake in an 8×8-inch pan. Check doneness at 40 minutes total, adding foil if the top browns too quickly.

Not as written, but you can substitute cubed gluten-free bread and use crisped rice cereal instead of corn flakes. Texture varies slightly but flavor remains stellar.

Look for puffed edges, a set center that jiggles only slightly, and the 195°F internal temperature. The top should be mottled gold, not deep brown.

Swap any good-melting cheese: Gruyère, Swiss, or Monterey Jack all work. Avoid pre-shredded Parmesan alone—it doesn’t melt smoothly and can toughen.

Cheesy Breakfast Casserole for New Year Day Brunch