This is the kind of casserole I make when I want something that feels special but isn’t high-effort. Assemble it the night before, sleep on it, and the oven does the rest in the morning. The custardy bread and crisp crumble make a comforting contrast that’s exactly what a slow, cozy brunch should be.

I trust sourdough for this — it holds its texture and soaks up the custard without turning to mush. The crumble on top adds a buttery crunch that keeps every bite interesting. It’s forgiving, too: little hands can help cube the bread, and you can prep the crumble while the oven comes up to temperature.

Below you’ll find a precise ingredient checklist from the original, a step-by-step How‑To that follows the tested method, and practical tips for success. No fuss, just a dependable recipe you can rely on for weekend mornings or easy holiday brunches.

Ingredient Checklist

Ingredients

3 Tbsp granulated sugar — sweetens the custard so the bread tastes rich but not cloying.
3/4 tsp ground cinnamon — adds warm spice to the custard.
1 pinch ground nutmeg — a little background warmth; a tiny pinch goes a long way.
6 large eggs — the structure for the custard, they bind everything together.
1 cup milk (anything but skim) — provides body to the custard; fuller milk makes a creamier result.
1 cup half-and-half — boosts richness without being heavy like cream.
1 1/2 tsp vanilla extract — lifts the custard with fragrant sweetness.
1 (14.5–16 oz) loaf sourdough bread, cut into 1-inch slices then slices cut into 1-inch cubes — sturdy bread that soaks yet holds texture.
2 Tbsp melted butter, plus more butter for baking dish — the melted butter is brushed on at the end; extra butter seasons the baking dish and prevents sticking.
Powdered sugar, for dusting (about 1 tsp) — optional finish for a gentle touch of sweetness and pretty presentation.
Real maple syrup or pancake syrup, for serving — your choice for finishing each square at the table.
1/3 cup (46 g) all-purpose flour — base of the crumble topping.
1/3 cup (78 g) packed light brown sugar — gives the crumble a deep, caramel note and helps it brown.
3/4 tsp ground cinnamon — the cinnamon for the crumble (separate from the custard cinnamon).
1/8 tsp salt — balances the sweetness in the crumble.
1/4 cup (56 g) unsalted butter, cold and diced into small cubes — cut into the dry crumble ingredients to create coarse, buttery crumbs.

Mastering Overnight French Toast Casserole: How-To

Butter a 13 x 9-inch baking dish with additional butter (use a little of the “plus more butter” from the ingredient list). Arrange the sourdough bread cubes (from the 14.5–16 oz loaf, cut into 1-inch slices and then 1-inch cubes) in an even layer in the dish.
In a mixing bowl with a pour spout, whisk together 3 Tbsp granulated sugar, 3/4 tsp ground cinnamon, and 1 pinch ground nutmeg.
Add all 6 large eggs to the sugar-spice mixture and whisk until well blended, scraping the bowl as needed.
Pour in 1 cup milk (not skim), 1 cup half-and-half, and 1 1/2 tsp vanilla extract. Whisk until the custard is smooth and fully combined.
Slowly and evenly pour the custard over the bread cubes, pausing and pressing down any dry pieces so they soak in the custard. If a few cubes remain dry, turn or dunk them into the custard in the dish.
Cover the baking dish tightly with plastic wrap and refrigerate overnight or for at least 10 hours.
About 30–45 minutes before baking, remove the casserole from the refrigerator. Preheat the oven to 350°F (175°C). Let the chilled casserole sit at room temperature for about 15 minutes while the oven preheats.
While the oven is preheating, make the crumble topping: in a medium bowl whisk together 1/3 cup (46 g) all-purpose flour, 1/3 cup (78 g) packed light brown sugar, 3/4 tsp ground cinnamon, and 1/8 tsp salt.
Add 1/4 cup (56 g) cold unsalted butter, diced into small cubes, to the dry mixture. Use a pastry cutter, two forks, or your fingertips to cut the butter into the flour mixture until it resembles coarse crumbs. If your oven is not yet fully preheated, place the crumble in the refrigerator until ready to use.
Sprinkle the crumble evenly over the top of the soaked bread in the baking dish.
Bake in the preheated 350°F oven until the casserole is set, the center is cooked through and no longer soggy, and the crumble is golden, about 38–45 minutes. Start checking at 38 minutes; a toothpick inserted in the center should come out mostly clean.
Remove from oven and let cool for a few minutes. Pour the 2 Tbsp melted butter evenly over the top. Dust with about 1 tsp powdered sugar if desired, cut into squares, and serve warm with real maple syrup or pancake syrup.

What You’ll Love About This Recipe

This casserole gives you soft, custardy centers and a crunchy, buttery top in one pan—no flipping, no single-serving fuss. Making it the night before means morning stress is minimal: pop it in the oven and relax while it bakes. The flavor is classic and familiar, with cinnamon and vanilla doing the heavy lifting, while the nutmeg adds a subtle depth.

The texture contrast is the real winner. The bread soaks up the custard but keeps some chew, and the crumble delivers a satisfying bite on each square. It’s perfect for serving a crowd or for a weekend when you want something comforting without being tied to the stove.

Quick Replacement Ideas

Real maple syrup or pancake syrup — choose whichever you prefer for serving; both are listed as options.
Powdered sugar — optional; skip it if you prefer a less sweet finish.
Milk and half-and-half balance — use the listed milk and half-and-half amounts as written for the intended custard richness.
Sourdough bread — the recipe is written specifically for the provided loaf size and cube size; stick to the instructions for best texture.

Appliances & Accessories

13 x 9-inch baking dish — the recipe is scaled for this size.
Mixing bowl with a pour spout — makes pouring the custard over the bread easier and neater.
Whisk — for blending the custard smoothly.
Pastry cutter, two forks, or clean fingertips — to cut the cold butter into the crumble mixture.
Plastic wrap — to cover the baking dish while it chills.
Oven — preheat to 350°F (175°C) as directed for baking.
Toothpick or skewer — to check doneness in the center.

Steer Clear of These

Using skim milk will give a thin, less creamy custard; the recipe specifies anything but skim for a reason. Don’t skip the chill time: the custard needs at least 10 hours to fully hydrate the bread. Overcrowding the dish with very small cubes will make it mushy; the 1-inch cube size is deliberate. Finally, avoid adding the crumble too early in the refrigeration step — the cold butter pieces stay intact and will make a better crumble if you assemble them just before baking.

Fresh Takes Through the Year

This casserole is a dependable base that plays well with seasonal accompaniments. In cooler months it pairs nicely with warm syrup and a dusting of powdered sugar for a cozy finish. In warmer seasons serve it simply with syrup and a lighter garnish — the core recipe needs little change to shine year-round.

If you want to bring a seasonal flair, keep the base recipe the same and let your toppings or sides do the work: warm on the side, cold on the side, sweet or slightly tart—the structure of the dish handles it all.

Little Things that Matter

Press dry cubes down into the custard so every piece gets a chance to soak. Letting the casserole sit at room temperature for about 15 minutes before baking helps it start to come up to temperature, which encourages even cooking. When making the crumble, work with cold butter and stop when you have coarse crumbs; overworking will warm the butter and change the texture.

Check doneness at the earliest recommended time. A mostly clean toothpick in the center means the custard is set but still tender. Finally, pouring the 2 Tbsp melted butter over the hot casserole after baking gives the top a glossy finish and deeper butter flavor.

Meal Prep & Storage Notes

This dish is designed to be prepped the night before; that’s the convenience. After baking, let it cool a few minutes before serving. Leftovers can be stored covered in the refrigerator. Reheat portions until warmed through and serve with syrup. For the best texture, reserve the powdered sugar dusting and any syrup for just before serving rather than storing them on top.

Final Thoughts

This Overnight French Toast Casserole is a practical, crowd-pleasing recipe that rewards a little planning with a simple, satisfying result. Follow the ingredient list and the step-by-step instructions for reliable texture and flavor every time. Prep before bed, bake in the morning, and serve warm with the syrup of your choice. It’s one of those recipes that becomes part of your regular rotation once you try it.

Overnight French Toast Casserole

Overnight sourdough French toast casserole with a cinnamon-nutmeg custard and a brown-sugar crumble; refrigerate overnight and bake until golden.

Print Recipe Pin Recipe

Prep Time 20

Cook Time 45

Total Time 1 5

Servings: 10 servings

Course: Breakfast

Cuisine: American

Ingredients Equipment Method Notes

Ingredients

3 Tbspgranulated sugar
3/4 tspground cinnamon
1 pinch ground nutmeg
6 large eggs
1 cupmilk anything but skim
1 cuphalf and half
1 1/2 tspvanilla extract
1 14.5 - 16 ozloaf sourdough bread*, cut into 1-inch slices then slices cut into 1-inch cubes*
2 Tbspmelted butter plus more butter for baking dish
Powdered sugar for dusting (about 1 tsp)
Real maple syrup or pancake syrup for serving
1/3 cup 46 gall-purpose flour
1/3 cup 78 gpacked light brown sugar
3/4 tspground cinnamon
1/8 tspsalt
1/4 cup 56 gunsalted butter, cold and diced into small cubes

Equipment

13 x 9-inch baking dish
mixing bowl with pour spout
Whisk
Plastic Wrap
Refrigerator
Oven
pastry cutter or forks
Toothpick

Method

Instructions

Butter a 13 x 9-inch baking dish with additional butter (use a little of the "plus more butter" from the ingredient list). Arrange the sourdough bread cubes (from the 14.5–16 oz loaf, cut into 1-inch slices and then 1-inch cubes) in an even layer in the dish.
In a mixing bowl with a pour spout, whisk together 3 Tbsp granulated sugar, 3/4 tsp ground cinnamon, and 1 pinch ground nutmeg.
Add all 6 large eggs to the sugar-spice mixture and whisk until well blended, scraping the bowl as needed.
Pour in 1 cup milk (not skim), 1 cup half-and-half, and 1 1/2 tsp vanilla extract. Whisk until the custard is smooth and fully combined.
Slowly and evenly pour the custard over the bread cubes, pausing and pressing down any dry pieces so they soak in the custard. If a few cubes remain dry, turn or dunk them into the custard in the dish.
Cover the baking dish tightly with plastic wrap and refrigerate overnight or for at least 10 hours.
About 30–45 minutes before baking, remove the casserole from the refrigerator. Preheat the oven to 350°F (175°C). Let the chilled casserole sit at room temperature for about 15 minutes while the oven preheats.
While the oven is preheating, make the crumble topping: in a medium bowl whisk together 1/3 cup (46 g) all-purpose flour, 1/3 cup (78 g) packed light brown sugar, 3/4 tsp ground cinnamon, and 1/8 tsp salt.
Add 1/4 cup (56 g) cold unsalted butter, diced into small cubes, to the dry mixture. Use a pastry cutter, two forks, or your fingertips to cut the butter into the flour mixture until it resembles coarse crumbs. If your oven is not yet fully preheated, place the crumble in the refrigerator until ready to use.
Sprinkle the crumble evenly over the top of the soaked bread in the baking dish.
Bake in the preheated 350°F oven until the casserole is set, the center is cooked through and no longer soggy, and the crumble is golden, about 38–45 minutes. Start checking at 38 minutes; a toothpick inserted in the center should come out mostly clean.
Remove from oven and let cool for a few minutes. Pour the 2 Tbsp melted butter evenly over the top. Dust with about 1 tsp powdered sugar if desired, cut into squares, and serve warm with real maple syrup or pancake syrup.

Notes

*I recommend using hearty bread like La Brea. Hearty French bread can be used as well.
*For easier, less messy cutting transfer bread to a plastic bag if it's in a paper bag and let it sit for a day. It makes cutting easier and less messy.
**If you don't have a mixing bowl with a pour spout at the end mixing you can transfer the egg mixture to a liquid measuring cup with a pour spout and pour it from there.
The casserole itself isn't that sweet so don't leave off the maple syrup. Syrup is not included in nutritional info.