Buttery, melt-in-your-mouth, tender, there truly aren’t enough adjectives to describe how delicious these Sourdough Blueberry Jam Bars are. Made with a homemade blueberry jam baked on top of a sourdough discard shortbread crust, these are a great way to use excess sourdough starter and packed berry flavor. I wanted to make these bars as simple as possible, so there’s no par baking required!
The blueberry preserves recipe is consistently one of the top recipes on my blog, and I’ve always wanted to make something that really puts it to good use. When Mimi and I picked blueberries as the theme for our May recipe collaboration, these sourdough blueberry shortbread bars felt like the perfect fit.
One of the best parts of our collaboration is the opportunity to test and refine each recipe before sharing it! Check out our other cookie recipes, Sourdough Peanut Butter Oatmeal Sandwich Cookies, Sourdough Red Velvet Cookies, Sourdough Jam Thumbprints and Sourdough Chocolate Shortbread Cookies.
Ingredients and Substitutions
All-purpose flour: The low protein content of all-purpose flour imparts delicate, melt-in-your-mouth texture to these cookies. Do not substitute another type of flour in this recipe. If you need help figuring out which flour to use in your recipes, check out my post on, The Best Flour for Sourdough.
Blueberries: I used fresh blueberries for this recipe, but you can use frozen or use 1 cup (226 grams) of store-bought jam if you don’t want to make your own filling.
Sourdough discard: Both active starter and sourdough discard work for this recipe. If you don’t have a sourdough starter, add 28 grams flour and 28 grams water to your dough.
Cornstarch: Absorbs excess moisture in the filling and crust so your bars don’t get soggy. I haven’t tested this recipe with another type of starch, so I can’t recommend a substitute for this ingredient.
Lemon: Bright citrus is a natural complement to blueberries. While the lemon isn’t essential, it adds a fresh, zesty note that really lifts the flavor. You’ll need 1 lemon, but it’s totally optional.
See recipe card for detailed ingredient information.
Step-by-step Instructions
STEP 1: Make the shortbread dough
Cream the butter with powdered sugar, vanilla extract and lemon zest until light and fluffy. Add in the sourdough discard and dry ingredients. Press ¾ of the dough into an 8-inch pan lined with parchment paper, and wrap the remaining dough in plastic. Chill for 30 minutes.
STEP 2: Make the filling
Make the filling as the dough chills. Combine the ingredients in a small saucepan and cook for 15 minutes, or until the blueberries break down and the mixture has thickened.
STEP 3: Assemble the bars
Layer the filling over the chilled shortbread dough. Break the remaining shortbread dough up on top of the filling, leave a few spots where the blueberry jam peaks through.
STEP 4: Bake and serve
Bake at 350 F for 45 minutes. Dust the bars with powdered sugar and divide them into 24 rectangles.
Baker’s Tips
- Weigh your ingredients. Measuring with a scale is much more accurate than using tablespoons and cups.
- Both sourdough discard and active sourdough starter will work for this recipe.
- Feel free to substitute 1 cup of store-bought jam thinned out with 1 tablespoon of water or fruit juice for the homemade blueberry filling.
- Lemon is a great addition to this recipe, but it is completely optional.
- Let the bars cool completely before dusting with powdered sugar and cutting.
Recipe FAQs
You can use active sourdough starter or just add 28 grams of flour and 28 grams of water or milk to your shortbread dough.
Absolutely! Feel free to use your favorite store-bought jam thinned with 1 tablespoon of water or fruit juice.
Yes! Substitute the berry of your choice by weight. You may need to adjust the cooking time of your filling since some fruits, like strawberries, contain more water and take longer to break down than blueberries.
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Sourdough Blueberry Jam Bars Recipe
Equipment
- pastry tamper optional
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Ingredients
Shortbread Dough
- 226 grams unsalted butter softened
- 150 grams powdered sugar
- 2 teaspoon vanilla extract
- zest from 1 lemon
- 56 grams sourdough discard
- 300 grams all-purpose flour
- 22 grams cornstarch
- ½ teaspoon salt
Bluberry Filling
- 226 grams fresh blueberries or frozen
- 100 grams granulated sugar
- 8 grams cornstarch
- 14 grams lemon juice
Topping
- Powdered sugar
Click US Customary to view volume measurements
Instructions
- Prep: Cut two pieces of parchment paper, about 8 by 15 inches, to create a sling for an 8-inch baking pan. Place them in the pan so they run perpendicular to each other. Set aside.
- Make the shortbread dough: Cream the butter with sugar, zest and vanilla until light and fluffy, about 3 minutes.226 grams unsalted butter, 150 grams powdered sugar, 2 teaspoon vanilla extract, zest from 1 lemon
- Add the sourdough discard and mix until well combined. Fold in the dry ingredients until a cohesive dough is forms.56 grams sourdough discard, 300 grams all-purpose flour, 22 grams cornstarch, ½ teaspoon salt
- Chill the dough: Press ¾ of the dough into the bottom of the prepared pan, making sure to press it into the corners.
- Wrap the remaining dough in a piece of plastic wrap. Refrigerate the pan and the remaining portion of dough (used for the topping) for at least 30 minutes.
- Prep: Preheat the oven to 350 F.
- Make the filling: While the dough chills, combine the filling ingredients in a small saucepan and stir. Cook over high heat until the blueberries begin to break down. Once the mixture boils, turn the heat down to medium and cook until the filling has thickened, about 15 minutes. Stir often to prevent the filling from burning.226 grams fresh blueberries, 100 grams granulated sugar, 8 grams cornstarch, 14 grams lemon juice
- Assemble the bars: Spread the warm blueberry filling evenly over the shortbread dough, making sure to get the filling into the corners.
- Break the remaining portion of shortbread dough over the filling, leaving a few spots where the blueberry filling still peaks through.
- Bake: Bake the bars for 40 to 45 minutes or until the shortbread topping looks lightly browned.
- Allow the bars to cool completely, dust with powdered sugar and slice it into a 6 by 4 grid, you should end up with 24 rectangles.Powdered sugar
- Store any leftover bars in an airtight container at room temperature for up to 5 days.
Tips
These recipes were developed and tested using grams for precise measurements. To increase your chances of success, I recommend investing in a kitchen scale. I've included rough volume estimates (in tablespoons and cups), but they might not be totally accurate.
Remember all ovens are unique, these recipes were tested in my oven which runs cooler than others. You might need to lower the temperature if your bake appears to be browning too quickly. Monitor your bake closely and make adjustments if needed.
Notes
- Both sourdough discard and active sourdough starter will work for this recipe.
- Feel free to substitute 1 cup of store-bought jam thinned out with 1 tablespoon of water or fruit juice for the homemade blueberry filling.
- Substitute the berry of your choice by weight. You may need to adjust the cooking time of your filling since some fruits, like strawberries, contain more water and take longer to break down than blueberries.
- Lemon is a great addition to this recipe, but it is completely optional.
- Let the bars cool completely before dusting with powdered sugar and cutting.
Nutrition
I am not a nutritionist or dietitian, any nutrition information provided is an estimate.
Did you make this recipe? Do you have questions? Let me know below!