Looking for a way to use that leftover sourdough bread? Making French toast from scratch can be time-consuming, especially when you’re hosting brunch for friends or family.

The last thing anyone wants is to be stuck in the kitchen flipping bread slices while guests wait.

I’ve got the perfect solution: a sourdough French toast casserole that you can prepare ahead of time. This recipe transforms day-old bread into a mouth-watering breakfast dish with minimal morning effort.

In this blog, I’ll share my foolproof recipe for the casserole, tips for getting that perfect custardy texture, and some topping ideas that will make your brunch truly special. You’ll also learn why sourdough bread makes this classic breakfast even better.

Why You’ll Love This Sourdough French Toast Casserole?

You’ll love this toast casserole for so many reasons! First, it’s a total time-saver. I make it the night before, so morning prep is almost non-existent. Just pop it in the oven and relax with coffee.

The sourdough bread adds a slight tang that balances the sweet custard perfectly. Unlike regular bread, it holds its shape and doesn’t turn mushy.

Clean-up is a breeze with just one baking dish instead of multiple pans and utensils. Plus, everyone can eat together instead of waiting for fresh batches.

It’s also incredibly adaptable. You can add nuts, fruits, or spices to match your mood or the season. Feeding a crowd? Simply double the recipe. Leftovers reheat beautifully for busy weekday mornings, too!

Ingredients & Tools: Best Sourdough French Toast Casserole

A warm, custardy casserole is the ultimate comfort food, crispy on top, soft in the center, and rich with flavor. If you’re serving brunch or prepping ahead for a cozy holiday morning, it brings rustic charm with every bite.

Key Ingredient

• Thick slices of sourdough bread (preferably day-old)
• Large eggs
• Whole milk or half-and-half
• Heavy cream (for extra richness)
• Pure vanilla extract
• Ground cinnamon and nutmeg
• Light brown sugar or maple syrup
• Unsalted butter
• Optional: cream cheese, fresh berries, chopped nuts

Key Tools

• 9×13-inch baking dish
• Whisk and mixing bowls
• Serrated bread knife (for clean cuts)
• Measuring cups and spoons
• Silicone spatula (for even spreading)
• Aluminum foil (for covering during baking)
• Refrigerator (for overnight soak, if prepping ahead)
• Oven and cooling rack

Step-by-Step: How to Make Sourdough French Toast Casserole

There’s something wonderfully comforting about the mix of sourdough, eggs, and warm spices. When those flavors come together in a baked casserole, it’s a breakfast worth waking up for.

This casserole is easy to prep, rich in flavor, and perfect for weekend brunch or holiday mornings.

Step 1: Cube the Sourdough Bread

Cut the sourdough into 1-inch cubes using a serrated knife. The bread should be slightly stale; fresh bread becomes mushy when soaked. If your loaf is too soft, toast the cubes lightly in the oven for 10 minutes at 300°F. Spread the cubes evenly in the greased baking dish once ready.

Step 2: Make the Custard Mixture

In a large mixing bowl, whisk together:

• 6 eggs
• 2 cups whole milk
• 1/2 cup heavy cream
• 1/2 cup maple syrup
• 1 tablespoon vanilla
• 1 teaspoon cinnamon
• 1/2 teaspoon salt

Mix until smooth and the eggs are fully incorporated. This mixture should be silky with no clumps or streaks of egg whites.

Step 3: Combine Bread and Custard

Pour the custard mixture evenly over the bread cubes. Press down gently with a spatula so the bread absorbs the liquid. Let it sit for 15 minutes at room temperature. For deeper flavor and better texture, cover the dish and refrigerate overnight to let it soak fully.

Step 4: Preheat and Add Topping

Preheat your oven to 350°F (175°C) while the casserole comes to room temperature. For an optional crunchy topping, mix:

• 1/4 cup brown sugar
• 2 tablespoons butter (melted)
• 1/4 cup chopped pecans
• 1/2 teaspoon cinnamon.

Sprinkle it evenly over the top before baking for added sweetness and texture.

Step 5: Bake to Golden Perfection

Place the casserole in the center of your preheated oven. Bake uncovered for 45–50 minutes, or until the top is golden brown and the center is set.

A knife inserted in the middle should come out clean. If browning too fast, loosely cover with foil during the last 10 minutes.

Step 6: Let It Rest and Serve

Once baked, remove the casserole from the oven and let it rest for 10 minutes. This helps the custard firm up slightly and makes slicing easier. Serve warm with extra maple syrup, fresh berries, or a dusting of powdered sugar. Leftovers can be stored in the fridge for up to 3 days.

Pro Tip: For a fall twist, add a layer of thinly sliced apples or pears between the bread layers before pouring the custard. It adds natural sweetness and pairs beautifully with cinnamon.

Different Topping Ideas for Sourdough French Toast Casserole

This casserole is delicious on its own, but the right topping can elevate it into something truly indulgent. If you’re craving a sweet, fruity finish or a warm, nutty crunch, there’s a topping to match every mood and occasion.

The following are five flavorful options to try:

Expert Tips for the Perfect French Toast Casserole

I’ve made this casserole dozens of times, and through plenty of trial and error, I’ve learned what makes the difference between good and amazing. The right techniques will give you that perfect balance of custardy inside and slightly crisp top that everyone loves.

Let me share my best advice to help you avoid common mistakes and take your breakfast casserole to the next level.

• Let the bread dry out: Fresh bread won’t absorb the custard as well; leave the cubes out for a few hours
• Soak overnight: At least 4 hours in the fridge, but overnight gives the best flavor fusion
• Use room temperature eggs: They blend more smoothly into the custard mixture
• Press bread down gently: Make sure all pieces contact the custard, but don’t smash them
• Bake covered, then uncovered: This prevents over-browning while ensuring it cooks through
• Check the center: It should be moist but not liquid; a knife should come out mostly clean
• Rest before serving: Let it sit for 10 minutes after baking to set properly
• Balance your add-ins: Too many extras can make the casserole too heavy
• Use a water bath: For extra creamy results, place your baking dish in a larger pan with hot water
• Adjust sugar to bread: If your sourdough is very tangy, you might want a bit more sweetness

Wrapping It Up

This sourdough French toast casserole has become my go-to recipe for both special occasions and lazy weekend mornings. It transforms simple ingredients into something truly special with minimal effort.

What makes this recipe stand out is its flexibility. You can stick to the classic version or add your creative spin with different toppings and mix-ins. The sourdough base provides that perfect structure that holds up beautifully to the rich custard.

I hope you’ll try this recipe soon and make it your own. The preparation is simple, the results are consistently good, and your family or guests will think you spent hours in the kitchen.

Don’t forget to share your experience in the comments below! I’d love to hear what topping combinations you tried and how everyone enjoyed this breakfast treat.