Buttery, flaky, naturally leavened croissants filled with sweet blueberry preserves. These sourdough blueberry croissants take a little patience, but the crisp layers and soft, flavorful center are absolutely worth it!
Ingredients
For the Dough
- 500 g bread flour
- 100 g active sourdough starter
- 200 g cold whole milk
- 75 g cold water
- 50 g granulated sugar
- 10 g salt
- 30 g unsalted butter, softened
For the Butter Layer
- 250 g unsalted European-style butter, cold
- 1 tablespoon flour
For the Blueberry Filling
- 200 g fresh or frozen blueberries
- 50 g granulated sugar
- 1 tablespoon lemon juice
- 1 tablespoon cornstarch
- 1 tablespoon water
For the Egg Wash
- 1 large egg
- 1 tablespoon milk
Step 1: Prepare the Dough
In a large bowl, combine the bread flour, active sourdough starter, milk, water, sugar, and salt.
Mix until a rough dough forms. Add the softened butter and knead for about 5–8 minutes, until the dough becomes smooth and elastic.
You don’t need to develop it completely like a bread dough—the dough should remain fairly firm.
Cover and let it rest at room temperature for about 30 minutes.
Then refrigerate the dough for 8–12 hours.
Step 2: Make the Blueberry Filling
Add the blueberries, sugar, and lemon juice to a small saucepan.
Cook over medium heat for about 5–7 minutes, stirring occasionally, until the berries soften and release their juices.
Mix the cornstarch with water to make a slurry. Stir it into the blueberries.
Cook for another 1–2 minutes until thick and jam-like.
Remove from the heat and let it cool completely.
Transfer to the refrigerator until ready to use.
Tip: The filling must be cold and thick before you add it to the croissants. A watery filling can leak during baking.
Step 3: Prepare the Butter Block
Place the cold butter between two sheets of parchment paper.
Gently pound and roll it into a rectangle approximately 20 × 15 cm.
Try to keep the thickness even throughout.
Place the butter block in the refrigerator while you prepare the dough.
Step 4: Roll Out the Dough
The next day, place the chilled dough on a lightly floured work surface.
Roll it into a rectangle approximately 40 × 20 cm.
Place the butter block in the center.
Fold the dough over the butter, completely enclosing it and sealing the edges.
Step 5: First Fold
Roll the dough into a long rectangle, approximately 60 × 20 cm.
Keep the pressure gentle and even so the butter doesn’t break through.
Fold the dough into thirds like a letter.
Wrap it tightly and refrigerate for 30–45 minutes.
Step 6: Second Fold
Take the chilled dough out and rotate it 90 degrees.
Roll it again into a long rectangle.
Fold it into thirds once more.
Wrap and refrigerate for another 30–45 minutes.
Step 7: Final Roll
Roll the dough into a rectangle approximately 90 × 20 cm, or as long and thin as you can comfortably manage.
The dough should be about 3–4 mm thick.
If the dough becomes too soft or the butter starts to feel greasy, stop and refrigerate it for 15–20 minutes.
Step 8: Cut the Croissants
Trim the edges to create a neat rectangle.
Cut the dough into long triangles with a base of approximately 9–10 cm.
Make a small slit in the center of the wide end of each triangle.
Place about 1 teaspoon of chilled blueberry filling near the wide end.
Don’t overfill—the filling can escape during baking.
Step 9: Shape the Croissants
Gently stretch each triangle slightly longer.
Starting from the wide end, roll it toward the tip.
Keep the roll loose enough to allow the layers to expand.
Place each croissant on a parchment-lined baking tray with the tip tucked underneath.
Curve the ends slightly toward the center if desired.
Step 10: Sourdough Proofing
Cover the croissants loosely and let them proof at room temperature.
Depending on the strength of your starter and the temperature of your kitchen, this can take approximately 4–8 hours.
Don’t rely only on the clock.
A properly proofed croissant should look noticeably puffy and airy. When you gently shake the tray, the croissants should jiggle slightly.
Step 11: Egg Wash
Whisk together the egg and milk.
Gently brush a thin layer over each croissant.
Try not to let the egg wash drip onto the cut edges, as this can interfere with the layers rising.
Step 12: Bake
Preheat your oven to 400°F (200°C).
Place the croissants in the oven and immediately reduce the temperature to 375°F (190°C).
Bake for approximately 20–25 minutes, or until deeply golden brown and crisp.
If they brown too quickly, loosely cover them with foil during the final few minutes.
Step 13: Cool and Serve
Let the croissants cool on a wire rack for at least 15–20 minutes before serving.
The outside should be crisp and beautifully golden, while the inside should have delicate, honeycomb-like layers with sweet blueberry filling.
Tips for Perfect Sourdough Blueberry Croissants
- Use a strong, active sourdough starter at its peak.
- Keep the dough and butter cold throughout the lamination process.
- Never let the butter melt into the dough.
- Chill the dough whenever it becomes difficult to roll.
- Use a thick blueberry filling rather than fresh loose blueberries.
- Don’t rush the final proof—the croissants need to become light and puffy.
- Bake until properly golden brown for the best texture.
Storage
Store baked croissants in an airtight container at room temperature for up to 2 days.
For the best texture, reheat them in a 350°F (175°C) oven for 5–8 minutes before serving.
They can also be frozen after shaping and before the final proof. Thaw, proof until puffy, then egg wash and bake.
