If you have a jar of sourdough discard hanging out in the fridge, this Sourdough Discard Blueberry Buckle is one of the best ways to use it. It’s soft, buttery, loaded with juicy blueberries, and topped with a sweet cinnamon crumble that gets wonderfully crisp in the oven. The sourdough discard adds a subtle tang that balances the sweetness without making the cake taste overly sour.
A blueberry buckle is somewhere between a coffee cake and a fruit-filled snack cake. As it bakes, the berries sink slightly into the tender batter while the crumbly topping creates that classic “buckled” look. It’s the kind of old-fashioned dessert that feels right at breakfast, afternoon coffee, or straight from the pan after dinner.
Ingredients
For the Blueberry Cake
- 1 cup all-purpose flour
- 1 teaspoon baking powder
- ½ teaspoon baking soda
- ¼ teaspoon salt
- ½ cup unsalted butter, softened
- ¾ cup granulated sugar
- 1 large egg
- 1 teaspoon vanilla extract
- ½ cup sourdough discard
- ¼ cup milk
- 1½ cups fresh or frozen blueberries
- 1 teaspoon lemon zest
For the Crumble Topping
- ½ cup all-purpose flour
- ⅓ cup granulated sugar
- ¼ cup unsalted butter, melted
- ½ teaspoon ground cinnamon
- Pinch of salt
Instructions
1. Prepare the Oven and Pan
Preheat your oven to 350°F (175°C). Grease an 8-inch square baking pan or line it with parchment paper, leaving a little overhang on the sides. The parchment makes it much easier to lift the finished buckle from the pan.
If you’re using frozen blueberries, there’s no need to thaw them first. Keeping them frozen helps prevent the berries from releasing too much juice into the batter.
2. Make the Crumble
Start with the topping so it’s ready to go when the batter is finished.
In a small bowl, combine the flour, sugar, cinnamon, and salt. Pour in the melted butter and stir with a fork until the mixture forms coarse crumbs. You want a mixture with some small crumbs and some larger chunks.
Set the crumble aside while you make the cake.
3. Mix the Dry Ingredients
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Give everything a good stir so the leavening ingredients are evenly distributed.
This quick step helps the cake rise evenly instead of having little pockets of baking soda or baking powder.
4. Cream the Butter and Sugar
In a large mixing bowl, beat the softened butter and sugar until light and fluffy, about 2–3 minutes.
Add the egg and vanilla extract and beat until smooth. Scrape down the sides of the bowl if needed.
The mixture should look creamy and slightly fluffy at this point.
5. Add the Sourdough Discard
Stir the sourdough discard into the butter mixture. Then add the milk and lemon zest.
The batter may look slightly curdled after adding the discard and milk. Don’t worry—that’s perfectly fine.
Gradually add the dry ingredients to the wet mixture. Stir just until combined. Avoid overmixing because too much stirring can make the finished buckle dense instead of tender.
6. Fold in the Blueberries
Gently fold the blueberries into the batter using a spatula.
If you’re using fresh blueberries, toss them with a teaspoon of flour first if you want to help keep them evenly distributed throughout the cake.
Be gentle here. You want those berries to stay whole and juicy.
7. Fill the Pan
Spread the batter evenly into your prepared baking pan.
Sprinkle the cinnamon crumble generously over the top. Don’t worry if the topping looks like a lot—it creates that irresistible crunchy layer as the buckle bakes.
8. Bake
Place the pan in the preheated oven and bake for approximately 40–50 minutes, or until the top is golden brown and a toothpick inserted into the center comes out mostly clean.
A little blueberry juice on the toothpick is okay, but you don’t want wet cake batter.
Because ovens vary, start checking around the 40-minute mark.
9. Cool and Serve
Allow the blueberry buckle to cool in the pan for at least 20–30 minutes before slicing.
It will continue to set as it cools, making it easier to cut into neat squares.
Serve it slightly warm with a cup of coffee, tea, or a cold glass of milk. For an extra-special treat, add a spoonful of whipped cream or vanilla ice cream.
Tips for the Best Sourdough Discard Blueberry Buckle
Use active or unfed discard: This recipe is designed for sourdough discard, so there’s no need to feed it first. Older discard will give the cake a slightly tangier flavor.
Fresh or frozen blueberries work: Both are delicious. If using frozen berries, add them straight from the freezer.
Don’t overmix: Once the flour goes in, stir only until you no longer see dry streaks. Overmixing can make the cake tough.
Watch the baking time: Blueberries release moisture as they bake, so the center may need a little extra time. The top should be golden and the center should look set.
Let it cool: As tempting as it is to cut into it immediately, giving the buckle time to cool helps the crumb firm up.
How to Store It
Store leftover blueberry buckle in an airtight container at room temperature for up to 2 days. For longer storage, refrigerate it for up to 5 days.
You can also freeze individual slices. Wrap each piece tightly and place them in a freezer-safe bag or container. Freeze for up to 3 months. Thaw at room temperature and warm briefly before serving.
