Lemon Blueberry Sourdough Toast

There's something about Saturday morning that makes me crave something more interesting than scrambled eggs, and this lemon blueberry sourdough French toast bake has become my answer to that craving. I discovered it by accident, really—I had a slightly stale loaf of sourdough, a container of blueberries threatening to go soft, and the sudden realization that a casserole might be easier than flipping individual slices while half-asleep. The first time I pulled it from the oven, the kitchen smelled like a bakery mixed with a lemon grove, and I knew I'd found something special.

I made this for my sister's birthday brunch last spring, and I watched my normally rushed morning transform into something almost leisurely. While the casserole baked, we sat on the porch with coffee, and by the time that golden-brown top emerged from the oven, everyone was actually gathered around the table instead of scrolling on their phones. That's when I understood this wasn't just a recipe—it was permission to slow down.

Ingredients

• Sourdough bread, cut into 1-inch cubes: The slight sourness in this bread is what makes the whole dish sing, cutting through the sweetness and adding complexity that white bread simply cannot deliver.
• Fresh or frozen blueberries, 1 ½ cups: Frozen works just as well as fresh and sometimes even better because they hold their shape—I learned this after a sad experience with fresh berries turning to mush.
• Lemon zest from 1 lemon: Don't skip this; it's what gives you that bright, morning-waking-up quality that makes people ask what you did differently.
• 6 large eggs: Room temperature eggs whisk smoother and create a silkier custard, so pull them from the fridge about 10 minutes before you start.
• Whole milk, 2 cups and heavy cream, ½ cup: This combination creates a custard that's rich but not heavy, with a texture that's almost silky on your tongue.
• Granulated sugar, ⅓ cup: This sweetens the custard without overwhelming it, leaving room for the other flavors to come through.
• Pure vanilla extract, 2 tsp: Real vanilla matters here because the subtle flavors in this dish need a partner that's equally refined.
• Salt, ¼ tsp: Just enough to make everything taste like itself and prevent the custard from tasting one-dimensional.
• Lemon juice from 1 lemon: Fresh lemon juice is essential; bottled has a sharp edge that tastes a little chemical compared to the brightness you get from squeezing it yourself.
• Unsalted butter, 2 tbsp melted: This goes on top for richness and helps create that golden, slightly crispy surface.
• Cinnamon-sugar topping: The spice adds warmth that complements both the lemon and blueberries in a way that feels almost surprising until you taste it.

Instructions

Prep your baking dish and bread:

Grease a 9x13-inch baking dish with butter or cooking spray, then arrange your sourdough cubes in an even layer—they should be snug but not packed tight so the custard can flow between them. Scatter your blueberries and lemon zest over the bread layer, letting the zest nestle into the crevices.

Whisk your custard together:

In a large bowl, crack your eggs and whisk them with the milk, cream, sugar, vanilla, salt, and fresh lemon juice until everything is completely combined and the mixture looks smooth and pale. This is the moment where you're essentially creating the magic that will transform bread into something creamy and custardy.

Pour and press gently:

Pour your custard mixture evenly over the bread and blueberries, then use the back of a spoon to press down lightly on the bread cubes—you're encouraging them to absorb all that eggy goodness without mashing them into oblivion. Let it sit for a minute so the bread has time to drink in the custard.

Chill and let it rest:

Cover the baking dish with plastic wrap or foil and refrigerate for at least 30 minutes, though overnight is genuinely better if you have the time. This waiting period lets the flavors mingle and ensures even cooking when it hits the oven.

Prepare for baking:

About an hour before you want to eat, preheat your oven to 350°F and let it come to temperature. While the oven heats, drizzle melted butter over the entire surface of the casserole, then mix your sugar and cinnamon together and sprinkle it evenly across the top.

Bake until golden:

Place the baking dish in your preheated oven and bake uncovered for about 45 minutes, until the center is set (it should jiggle just slightly in the middle if you give it a gentle shake) and the top is a deep golden brown. The edges will be slightly puffed and the kitchen will smell like you've opened the doors to heaven.

Cool before serving:

Let it rest for 10 minutes after it comes out of the oven so it sets up properly and becomes easier to portion. Serve it warm with a drizzle of maple syrup or a light dusting of powdered sugar if you want to gild the lily.

Save

My neighbor came over unexpectedly one Sunday morning, and instead of feeling flustered, I simply slid this into the oven and we sat talking while it baked. When we sat down to eat, she took one bite and got quiet in that way people do when something tastes exactly right, and I realized this dish has this quiet power to make ordinary moments feel intentional and special.

Why Sourdough Makes All the Difference

I've tried this with regular white bread out of desperation once, and while it was fine, it was just fine—pleasant and forgettable. Sourdough brings this subtle tang that prevents the dish from tasting too sweet and gives it depth that makes you want another bite. The texture is also different; sourdough's slightly chewy structure holds up to the custard better than soft bread would, creating pockets of flavor rather than a mushy mass.

Timing and Make-Ahead Strategy

The beauty of this casserole is that it actually improves when you refrigerate it overnight because the custard has more time to seep into every corner of the bread. You can assemble it on Friday night, cover it, and Saturday morning just drizzle the butter on top and slide it into the oven while you shower or drink your first coffee. For a dinner party, you could even prep it in the afternoon and bake it an hour before guests arrive, serving it warm and impressive.

Flavor Variations and Personal Touches

Once you understand the formula, you can play with it—raspberries bring tartness where blueberries bring sweetness, and blackberries add an almost earthy sophistication. I've experimented with adding a pinch of cardamom to the custard, and it transforms the whole thing into something that feels a little more exotic. Some mornings I add a splash of lemon liqueur to the custard or swap the cinnamon sugar topping for crushed candied lemon peel for something more adventurous.

• Try using half regular milk and half Greek yogurt mixed into your custard for extra richness and a subtle tang.
• A light glaze made from powdered sugar and lemon juice drizzled over the warm casserole adds visual appeal and extra lemon flavor if you're craving it.
• If you want to make it feel more indulgent, top individual servings with whipped cream or a dollop of crème fraîche instead of powdered sugar.

Save

This casserole has become my go-to when I want to feed people something that tastes like I've fussed over it for hours when really I spent fifteen minutes prepping. It's the kind of dish that makes weekends feel less rushed and more intentional, which might be the best thing any recipe can do.

Kitchen Q&A

→ What type of bread works best for this dish?

Sourdough bread is preferred due to its texture and flavor, but any sturdy artisan bread cut into cubes should work well.

→ Can fresh blueberries be substituted with frozen?

Yes, frozen blueberries can be used directly without thawing, keeping the burst of berry flavor intact.

→ How long should the soaking step last for best texture?

Refrigerate the custard-soaked bread mixture for at least 30 minutes, or ideally overnight, for thorough soaking and a custardy interior.

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

Substitute the milk and cream with plant-based alternatives like almond or oat milk while maintaining the custard texture.

→ What toppings complement this baked dish?

Melted butter combined with cinnamon and sugar creates a crisp, sweet topping, while optional maple syrup adds extra richness.

→ How should leftovers be stored and reheated?

Store leftovers covered in the refrigerator up to 3 days; reheat gently in the oven or microwave before serving.