The Sourdough French Toast Casserole That Makes Christmas Morning Extra Special

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All the flavors of French toast — the vanilla, the cinnamon, the custard — baked into one dish instead of standing at the stove flipping individual slices. This is the breakfast you make when you want something special without the effort, or when you’re feeding a crowd and need everything ready at once.

Assemble it the night before, bake it in the morning, and breakfast is done.

Ingredients

• 8 slices sourdough bread, cut into cubes (about 12 cups)
• 3 large eggs
• ¾ cup whole milk
• 1 tablespoon granulated sugar
• 1 teaspoon vanilla extract
• ½ teaspoon ground cinnamon
• ¼ teaspoon salt
• 2 tablespoons butter, for greasing

Step-by-Step Instructions

Step 1: Preheat and Prep

Preheat your oven to 350°F (175°C). Grease a baking dish generously with butter — a 9×13 inch dish or similar works well.

Step 2: Add the Bread

Cut the sourdough into rough cubes and spread them evenly across the prepared baking dish. Day-old or slightly stale sourdough works best here — it absorbs the custard without turning mushy.

Step 3: Make the Custard

In a bowl, whisk together the eggs, milk, sugar, vanilla extract, cinnamon, and salt until completely smooth and well combined.

Step 4: Soak the Bread

Pour the custard evenly over the bread cubes, making sure every piece gets coated. Press the bread down gently with the back of a spoon so the cubes absorb the liquid. Let the mixture sit for 20–30 minutes — this soaking time makes a noticeable difference to the final texture.

If you’re short on time, you can skip it, but the overnight method is best of all.

Step 5: Bake

Bake for 30–35 minutes until the top is golden brown and the center is set — it should feel firm rather than jiggly when you gently shake the dish. A toothpick inserted in the center should come out clean.

Step 6: Rest and Serve

Let the casserole cool for 5–10 minutes before serving. It firms up slightly as it cools and is much easier to portion. Serve with maple syrup, powdered sugar, fresh berries, or yogurt.

Pro Tips

Use day-old or stale sourdough. Fresh bread can become too soft and wet. Bread that’s one to two days old absorbs the custard beautifully without losing its structure. If your bread is very fresh, spread the cubes on a baking sheet and leave them out uncovered for an hour before using.

Don’t skip the soak. Even 20 minutes makes a real difference — the custard penetrates further into the bread and the finished casserole has a more uniform, custardy texture throughout. The overnight soak in the fridge gives the very best result.

Press the bread down after pouring. Every cube should have contact with the custard. Press gently all over after pouring to make sure nothing is sitting dry on top.

Check the center before pulling from the oven. The casserole is done when the center feels set and doesn’t wobble. If the top is golden but the center is still soft and jiggly, cover loosely with foil and give it another 5–8 minutes.

Let it rest before serving. The structure firms up significantly in the first 5–10 minutes after coming out of the oven. Cutting into it immediately gives you a loose, falling-apart result. A brief rest gives you clean, defined portions.

Variations & Customizations

• Make it overnight — Assemble the full casserole, cover, and refrigerate overnight. In the morning, pull it from the fridge while the oven preheats and bake as directed. The overnight soak gives the best flavor and texture of all.
• Add fresh or frozen berries — Scatter blueberries, raspberries, or diced strawberries over the bread before pouring the custard. They bake into the casserole and add pops of fruit throughout.
• Add sliced apples or pears — Toss thin slices of apple with a pinch of cinnamon and brown sugar and layer them through the bread cubes before pouring the custard for a fruit-forward variation.
• Add a streusel topping — Mix 3 tablespoons of flour, 3 tablespoons of brown sugar, 1 teaspoon of cinnamon, and 2 tablespoons of cold butter into crumbs and scatter over the top before baking for a crunchy, bakery-style finish.
• Make it richer — Replace the milk with half-and-half or a combination of milk and cream for a denser, more indulgent custard.
• Maple brown butter drizzle — Brown 2 tablespoons of butter in a small saucepan until nutty and golden, then stir in 2 tablespoons of maple syrup. Drizzle over the baked casserole just before serving.

Storage & Reheating

Method	Details
Fridge	Store covered in an airtight container for up to 3 days.
Reheating	Reheat in a 325°F oven for about 10 minutes until warmed through. Individual portions can be microwaved for 30–45 seconds.
Freezer	Freeze individual portions for up to 2 months. Thaw overnight in the fridge and reheat in the oven for the best texture.

Frequently Asked Questions

Can I use stale bread?

Yes — slightly stale sourdough is actually ideal. It absorbs the custard without becoming overly soft and mushy. Very fresh bread tends to get soggy. If you only have fresh bread, spread the cubes on a baking sheet and leave them out for an hour or two to dry out slightly before using.

Can I prepare this the night before?

Yes, and it’s the recommended approach. Assemble the dish, press the bread down, cover tightly with plastic wrap or foil, and refrigerate overnight. In the morning, remove from the fridge while the oven preheats and bake as normal. The overnight soak gives the most evenly custardy, deeply flavored result.

Can I add fruit?

Yes. Blueberries, raspberries, diced strawberries, or thinly sliced apple all work beautifully. Add them on top of or layered through the bread before pouring the custard over.

Why is my casserole soggy in the middle?

Either the bread didn’t have enough time to absorb the custard before baking, or it needed a few extra minutes in the oven. If the center is set on top but wet underneath, cover with foil and bake for another 5–8 minutes. The overnight soak helps prevent this by ensuring even absorption throughout.

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