Blueberry Lemon Sourdough Toast

My neighbor knocked on my door one Saturday morning with a container of the most beautiful fresh blueberries, apologizing for the abundance from her garden. I stood there holding them, thinking about breakfast, thinking about the sourdough I'd neglected in my fridge, and suddenly I wanted to make something that felt celebratory but also effortless. That's when this casserole came together—a dish that lets you prep everything the night before and still feel like you've accomplished something magical when your guests arrive.

I made this for my book club last spring, and what started as a simple brunch turned into everyone lingering at the table for three hours, forks in hand, asking for seconds. One friend actually closed her eyes while eating it, and I realized then that the combination of tangy sourdough, bright citrus, and those pops of blueberry had somehow become comfort food and celebration all at once.

Ingredients

• Sourdough bread, cut into 1-inch cubes (about 1 loaf, 400g): Day-old sourdough is your secret weapon here—fresh bread will turn to mush, but bread that's been sitting overnight absorbs the custard without falling apart, and the tang of the sourdough becomes even more pronounced when it mellows into the egg mixture.
• Fresh blueberries (2 cups): If you're using frozen, don't thaw them first—frozen berries hold their shape better and won't bleed as much color into the custard.
• Lemon zest (from 1 large lemon): Use a microplane or fine grater to get those delicate ribbons of brightness that distribute throughout every bite.
• Large eggs (6): These are what transform bread into something custard-like and custardy, so don't be tempted to skip any.
• Whole milk (2 cups): The fat content matters here—whole milk creates a richer custard than low-fat versions ever could.
• Heavy cream (3/4 cup): This is what makes the texture silky and indulgent without feeling heavy.
• Granulated sugar (1/2 cup): It sweetens the custard and helps it set properly as it bakes.
• Pure vanilla extract (2 tsp): Use real vanilla, not imitation—you can actually taste the difference in a custard-based dish like this.
• Ground cinnamon (1/2 tsp): A whisper of warmth that complements the lemon without overpowering it.
• Fine sea salt (1/4 tsp): Salt is the thing nobody talks about but everyone tastes—it amplifies the other flavors.
• Lemon juice (from 1 lemon): Fresh juice adds brightness that bottled lemon juice simply cannot match.
• Sliced almonds (1/2 cup, optional): If you're using these, they add a gentle crunch that contrasts beautifully with the soft custard.
• Turbinado or coarse sugar (2 tbsp, optional): Scatter these over the top before baking if you want pockets of sugar crunch.
• Powdered sugar for dusting: This creates a snowlike finish and adds a final sweetness.
• Maple syrup or lemon curd for serving: Choose whichever feels right for your mood—syrup is classic and warm, while lemon curd doubles down on that bright citrus note.

Instructions

Prepare your baking dish:

Grease a 9x13-inch baking dish generously with butter or nonstick spray, making sure to get into all the corners and edges so nothing sticks.

Build your layers:

Spread half the sourdough cubes in an even layer across the bottom of the dish, then scatter half the blueberries and half the lemon zest over top. Repeat with the remaining bread, berries, and zest, creating a loose, layered effect rather than trying to pack everything tightly.

Make the custard:

In a large bowl, whisk together the eggs, milk, cream, granulated sugar, vanilla, cinnamon, salt, and lemon juice until the mixture is smooth and well combined—you're looking for no streaks of egg white anywhere. This should take about a minute of steady whisking.

Soak the bread:

Pour the custard slowly and evenly over the bread and blueberries, then use the back of a spatula or a gentle hand to press down on the bread so it's submerged and can start absorbing the liquid immediately. Don't be aggressive—just enough pressure to get the bread sitting in the custard.

Chill overnight or for at least 30 minutes:

Cover the dish with plastic wrap and refrigerate for a minimum of 30 minutes, though overnight is truly best because the bread has more time to absorb all that custardy goodness. This is the step that makes this dish perfect for entertaining—you do the work the night before and bake it the next morning.

Preheat and prepare the oven:

When you're ready to bake, preheat your oven to 350°F and let it come fully to temperature—a cold oven will bake unevenly. If you want almonds and turbinado sugar on top, scatter them over now.

Bake until golden and set:

Bake uncovered for 45 to 50 minutes, until the top is puffed and golden brown and a knife inserted in the center comes out with just a tiny bit of custardy coating—it should be mostly set but still have that tender quality. The edges will look slightly crispy, which is perfect.

Rest and finish:

Remove from the oven and let it sit for 10 minutes—this allows the custard to set up a bit more and makes it easier to serve. Dust generously with powdered sugar just before serving, then drizzle with maple syrup or lemon curd depending on which direction your heart is pointing.

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There's something quietly wonderful about serving a hot, fragrant casserole to a table of people and watching their faces light up when they taste it. It's become the dish I make when I want to show people I care but don't want to fuss—which, looking back, might be the most honest kind of hospitality.

Why Sourdough Changes Everything

Using sourdough instead of brioche or regular white bread transforms this from a sweet breakfast into something with actual character. The mild tang plays against the lemon in a way that makes both flavors brighter, and the bread's sturdy crumb structure means it can handle absorbing all that custard without disintegrating. If you've only ever made French toast casserole with soft bread, this version will surprise you with how much more interesting it tastes.

The Blueberry-Lemon Chemistry

I learned by accident that blueberries and lemon were meant to be together when I was making a cake years ago. That discovery has stayed with me, and it's the reason this casserole works so well—the tartness of the lemon makes the blueberries taste more blueberry-like, and the blueberries add a sweetness that softens the sharpness of the citrus. It's a balance that feels elegant without being fussy, which is exactly the kind of breakfast that makes people want to linger.

Make It Your Own and Serve It With Style

This casserole is also incredibly forgiving when it comes to variations, which is part of why I love it. You can swap raspberries or blackberries for some or all of the blueberries, use orange zest instead of lemon if you're feeling different, or make it dairy-free by swapping almond milk and coconut cream for the milk and cream. Serve it warm from the oven with a sharp sparkling wine or a mimosa, or just with strong coffee and good conversation.

• If you want maximum crunch, add the almonds and turbinado sugar only in the last 10 minutes of baking so they don't brown too much.
• A drizzle of lemon curd over the powdered sugar creates an extra citrus punch that some people find absolutely irresistible.
• Leftovers keep beautifully for a couple of days and can be gently reheated in a low oven without drying out.

Save

This casserole reminds me every time I make it that the best dishes are the ones that feel both special and simple, the ones where you can actually enjoy the morning instead of being stuck in the kitchen. Make this when you want to feel like you've done something lovely for the people you're feeding.

Recipe FAQs

→ Can I use frozen blueberries?

Yes, you can use frozen blueberries without thawing. They will release juices during baking, adding to the flavor and moisture.

→ What bread works best?

Day-old sourdough is ideal because it soaks up the custard well without becoming too soggy, providing a sturdy yet tender texture.

→ How can I add crunch to the dish?

Sprinkling sliced almonds and coarse sugar on top before baking adds a delightful crunchy contrast to the soft interior.

→ Is there a dairy-free variation?

Yes, substitute whole milk and cream with almond or oat milk and coconut cream to maintain richness without dairy.

→ Can this be prepared ahead?

Absolutely. After assembling, refrigerate for at least 30 minutes or overnight to let flavors meld and the bread absorb the custard fully.