Blueberry Lemon Sourdough Toast

There's something magical about how sourdough transforms in a custard bath. My neighbor brought this casserole to a Sunday brunch last spring, and I watched it emerge from the oven all golden and puffed, the blueberries peeking through like little jewels. She mentioned casually that the tang of the sourdough played beautifully against the brightness of lemon, and I was sold immediately. Now it's become my go-to when I need something that looks impressive but feels genuinely easy to pull off.

I made this for my sister's birthday brunch two years ago, and she actually cried a little bit when she took the first bite. She said it tasted like sunshine and comfort at the same time, which sounds silly until you experience that bright lemon-and-blueberry combination hitting your taste buds while you're sitting in pajamas with good coffee. That moment taught me that breakfast food deserves just as much care and creativity as anything else you cook.

Ingredients

• Sourdough bread, 1 loaf cut into 1-inch cubes: The sourness here is your secret weapon—it prevents the casserole from tasting one-note sweet, and day-old bread absorbs the custard like a dream.
• Fresh blueberries, 2 cups: Use frozen and unthawed if fresh aren't available; they'll stay firmer and won't turn the custard purple.
• Lemon zest, from 1 large lemon: Don't skip this—the zest carries more flavor than the juice alone and adds brightness in every bite.
• Eggs, 6 large: These are your binder and what makes everything custard-y and tender, so please use large eggs, not medium.
• Whole milk, 2 cups: This is the base that carries all the flavor, so use something you'd actually drink.
• Heavy cream, 3/4 cup: The richness is essential; don't try to substitute with evaporated milk or it'll taste lean.
• Granulated sugar, 1/2 cup: Balance matters here—too little and you lose the sweetness, too much and you lose the lemon brightness.
• Pure vanilla extract, 2 tsp: Real vanilla makes a noticeable difference in the custard's depth.
• Ground cinnamon, 1/2 tsp: A whisper of warmth that makes people say, 'Is that cinnamon?' without being able to place it.
• Fine sea salt, 1/4 tsp: Salt rounds out all the flavors and prevents the custard from tasting flat.
• Lemon juice, from 1 lemon: The juice acidifies the custard slightly and enhances the overall brightness.
• Sliced almonds, 1/2 cup optional: These add crunch and keep the top from getting soggy if you're serving leftovers.
• Turbinado or coarse sugar, 2 tbsp optional: The larger crystals catch the heat and create a subtle crunch on top.
• Powdered sugar for dusting: A light dusting just before serving adds visual appeal and a final gentle sweetness.
• Maple syrup or lemon curd for serving: Choose based on mood—maple syrup is comforting, lemon curd doubles down on brightness.

Instructions

Perfect for simmering soups, baking casseroles, and serving cozy one-pot meals straight from oven to table.

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Prepare your dish:

Grease a 9x13-inch baking dish generously with butter or nonstick spray, getting into the corners. This prevents sticking and ensures even browning on the edges.

Layer the bread and berries:

Spread half your sourdough cubes across the bottom, then scatter half the blueberries and half the lemon zest over top. Repeat with the remaining bread, berries, and zest in an even layer. This distribution ensures every bite has blueberries and brightness.

Make the custard mixture:

In a large bowl, whisk together eggs, milk, cream, sugar, vanilla, cinnamon, salt, and lemon juice until completely smooth with no egg streaks visible. Take your time here—a thoroughly whisked custard cooks evenly.

Soak the bread:

Pour the custard evenly over the bread and blueberries, then gently press down with a spatula so the bread cubes absorb the liquid. You want the bread to drink it all in, not float on top.

Chill and plan ahead:

Cover with plastic wrap and refrigerate for at least 30 minutes, though overnight is ideal. The longer it sits, the more the bread absorbs the custard, resulting in a creamy, cohesive casserole rather than a bready one.

Heat your oven:

When you're ready to bake, preheat to 350°F. This moderate temperature allows the custard to set gently without the edges browning too quickly.

Add the topping:

If you're using almonds and turbinado sugar, sprinkle them evenly over the top just before it goes into the oven. They'll toast as the casserole bakes, adding texture and richness.

Bake to golden perfection:

Bake uncovered for 45 to 50 minutes, until the top is puffed and golden and the center feels set when you gently shake the dish. It should jiggle just slightly, not slosh.

Rest and serve:

Let it rest for 10 minutes—this lets the custard set properly and makes it easier to serve cleanly. Dust generously with powdered sugar and serve warm with maple syrup or lemon curd alongside.

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One morning I was making this and my kids wandered into the kitchen just as it came out of the oven, filling the whole space with this warm, lemony, toasty smell. They asked if they could have some for breakfast, and suddenly it wasn't just a casserole anymore—it was permission to eat dessert for breakfast, which felt like a small kind of magic. That's the moment I realized this recipe works because it feels indulgent but tastes honest.

Why Sourdough Changes Everything

Sourdough has a built-in complexity that sweeter breads don't have. The fermentation creates tangy notes that interact beautifully with lemon and custard, and the crumb structure is sturdy enough to soak up liquid without turning to mush. Regular sandwich bread would make this taste one-dimensional and overly sweet, but sourdough gives it sophistication without any extra work on your part.

The Lemon Component Matters More Than You Think

Don't treat the lemon as optional flavoring. The zest carries essential oils that create brightness, while the juice adds a subtle acidic note that prevents the custard from tasting flat or cloying. Together, they're what make people pause mid-bite and notice they're tasting something interesting. I learned this the hard way when I once made it without fresh lemon juice, using extract instead, and it tasted distinctly flat despite everything else being exactly the same.

Make It Your Own

This casserole is forgiving enough to handle variations while staying true to its soul. The framework of sourdough plus tart fruit plus custard works with raspberries, blackberries, or even stone fruit, and a dairy-free version using oat milk and coconut cream tastes genuinely good, not like a compromise. The beauty of a casserole is that it's built for flexibility once you understand what's actually doing the heavy lifting flavor-wise.

• Substitute raspberries or blackberries for blueberries if you prefer a different tartness level.
• For dairy-free, swap almond or oat milk for whole milk and coconut cream for heavy cream in equal amounts.
• Add 1/2 teaspoon of cardamom or a touch of orange zest if you want to layer in additional warmth or brightness.

Rinse produce, fill pots, and clean cookware easily with flexible spray options for everyday cooking tasks.

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This casserole exists in that beautiful space where it's fancy enough for guests but simple enough for a regular Sunday morning. Once you've made it, you'll find yourself returning to it again and again.

Recipe FAQ

→ What type of bread works best for this dish?

Day-old sourdough bread cut into 1-inch cubes is ideal as it soaks up the custard well without becoming too soggy.

→ Can I use frozen blueberries instead of fresh?

Yes, frozen blueberries can be used without thawing, preserving their texture and flavor during baking.

→ Is there a way to make this dairy-free?

Substitute whole milk with almond or oat milk and replace heavy cream with coconut cream for a dairy-free version.

→ How long should the dish rest before baking?

Refrigerate the assembled dish for at least 30 minutes to allow the bread to fully absorb the custard mixture. Overnight chilling enhances flavor.

→ What toppings complement this bake?

Sliced almonds and turbinado sugar add a delightful crunch. Finished with powdered sugar and served with maple syrup or lemon curd, it balances sweet and tangy notes.