Sourdough Lemon Bars

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Tart and sweet lemon bars made with sourdough discard in the filling and in the crust. These sourdough lemon bars will be a hit at your next gathering or anytime you're in the mood for a sweet shortbread crust with a creamy lemon topping. Absolutely delicious!

Sweet, tart and tangy but best of all made with sourdough discard in the filling AND the crust. These sourdough discard lemon bars are incredibly delicious. I sliced them into small squares and brought them to a recent gathering and I didn’t bring ANY home – not one! The perfect combination of lemon filling and a buttery shortbread crust. You are going to love these sweet sourdough lemon bars.

Why You’ll Love Sourdough Discard Lemon Bars

You will love this recipe first and foremost because it tastes delicious. It’s creamy and tart with the shortbread texture underneath that make these a satisfying treat. Perfect for a spring or summer day, you’re going to love serving these sourdough lemon bars to your family and friends.

Important Ingredients in Sourdough Discard Lemon Bars

  • Sourdough Discard: Sourdough discard is used in both the lemon filling and the shortbread base. Use 100% hydration sourdough discard in these lemon bars. Discard that is younger and more fresh will taste better in these bars. For more sour flavor, use older discard. You can also substitute fresh, bubbly sourdough starter for the discard in this recipe.
  • Unsalted Butter: I always bake with unsalted butter so I can adjust the salt content myself.
  • Granulated Sugar: Granulated sugar counteracts the sour lemon and adds sweetness to these lemon bars for the perfect balance of flavors.
  • All-Purpose Flour: Use an all-purpose or pastry flour for the crust of the bars.
  • Lemons: Freshly squeezed lemons and lemon zest give these bars their lemon flavor. It is worth juicing your own lemons and using fresh lemon zest.
  • Eggs: Eggs are mixed with the liquid ingredients and baked in the oven to form a creamy lemon curd filling.
  • Whole Milk: A little whole milk makes these lemon bars extra creamy and delicious.
  • Vanilla Extract
  • Salt

How to Make Sourdough Discard Lemon Bars

Shortbread Crust

Mix together softened/melty butter and granulated sugar. Scrape down sides as needed. Add the sourdough discard and mix again until completely incorporated. Then add the vanilla extract and salt and mix again. Lastly, add the flour and mix until soft chunks of dough form. Pour the chunks of dough into a parchment-lined baking pan.

  • Pre-heat the oven to 325ºF. Line an 8 by 8 pan with parchment paper.
  • To a medium-sized bowl add softened butter and granulated sugar. Mix with a hand mixer for about a minute, scraping down the sides as needed until light and fluffy. Add the sourdough discard and mix again until the discard is completely incorporated into the butter/sugar mixture. Add vanilla extract and salt. Mix again. Add the flour and mix until soft chunks of dough form.
  • Pour the dough into the lined baking pan. Use your fingers to press the mixture into an even layer on the bottom of the pan. Prick the shortbread crust. Bake for 25-30 minutes until the edges start to brown and the shortbread crust is baked through.

Lemon Filling

Whisk together the eggs, sugar and sourdough discard in a small bowl. Incorporate the discard until it’s completely smooth. Zest in a lemon and pour in the freshly squeezed lemon juice. Whisk to combine. Add the milk and whisk again. Pour the lemon filling on top of the warm shortbread crust – straight from the oven.

Baking and Chilling the Bars

Bake sourdough lemon bars for about 30-35 minutes. The lemon bars are set when the middle doesn’t jiggle or wobble. Let the bars cool for about an hour and then put the bars in the refrigerator to chill. Lemon bars should chill for about 2 hours until completely cold or overnight. Once the bars are chilled, slice into squares and dust with powdered sugar right before serving.

Amy’s Recipe Tip

  • In order for the texture of the bars to set up just right, make sure to serve the lemon bars chilled. This helps the filling set up and the crust crisp up.
  • A great tip for getting a clean cut on the chilled lemon bars is to run a sharp knife under hot water. Dry the knife with a paper towel and slice into squares. Wipe the knife as needed and repeat with warm water if you notice the bars sticking to the knife.

Substitutions

  • Butter: I use unsalted butter in this recipe. If you choose to substitute with salted butter, decrease the salt to 1/4 teaspoon or leave it out completely.
  • Whole Milk: Substitute 2% milk

How to Store Leftovers

Lemon bars can be stored in the fridge, covered in an airtight container for 5-7 days. They can also be frozen for 2-3 months. You may want to blot any condensation from the top of the bars and re-dust with powdered sugar.

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Frequently Asked Questions

Help! My lemon bars looked like scrambled eggs?

If this happened to you, the heat of the oven is most likely the culprit. Make sure the liquid ingredients are fully combined before pouring on top of the shortbread crust. These lemon bars are baked at a low temperature so the filling will bake up evenly. If your oven runs hot, you will need to decrease the temperature to bake these lemon bars.

A little liquid started pooling on my lemon bars before serving them.

This can happen because the bars are being stored in the refrigerator. Blot lemon bars with a paper towel. Then dust with powdered sugar right before serving.

This bar had too much shortbread crust. Can I decrease it?

I like the ratio of shortbread to lemon filling in this bar, but if you want less shortbread, decrease the recipe by about 1/4 – 1/3 and you will have a thinner bar layer.

The powdered sugar evaporated!

This can happen when the bars are chilled if water forms on the bars. Dust sourdough lemon bars with powdered sugar right before serving.

Sourdough Lemon Bars

Amy
Tart and sweet lemon bars made with sourdough discard in the filling and in the crust. These sourdough lemon bars will be a hit at your next gathering or anytime you're in the mood for a sweet shortbread crust with a creamy lemon topping. Absolutely delicious!
5 from 2 votes
Prep Time 20 minutes
Cook Time 1 hour
Total Time 1 hour 20 minutes
Course Dessert
Cuisine American
Servings 16 bars

Ingredients
  

Shortbread Crust

  • 150 grams unsalted butter, softened or melty about 11 Tablespoons
  • 75 grams granulated sugar about 1/3 cup plus 1 Tablespoon
  • 50 grams sourdough discard 100% hydration, see recipe notes
  • 6 grams vanilla extract about 1 1/2 teaspoons
  • 3 grams salt about 1/2 teaspoon
  • 210 grams all-purpose flour about 1 1/2 cups

Creamy Lemon Bar Filling

  • 3 large eggs about 150 grams
  • 200 grams granulated sugar about 1 cup
  • 60 grams sourdough discard 100% hydration, see recipe notes
  • 6 grams lemon zest zest from one large lemon, about 1 Tablespoon
  • 110 grams freshly squeezed lemon juice juice from 2 large lemons, about 1/2 cup
  • 80 grams milk whole or 2%, about 1/3 cup

Instructions
 

Shortbread Crust

  • Pre-heat the oven to 325ºF. Line an 8 by 8 pan with parchment paper.
  • To a medium-sized bowl add softened/melty butter and granulated sugar. Mix with a hand mixer for about a minute, scraping down the sides as needed until light and fluffy. Add the sourdough discard and mix again until the discard is completely incorporated into the butter/sugar mixture. Add vanilla extract and salt. Mix again. Add the flour and mix until soft chunks of dough form.
  • Pour the dough into the lined baking pan. Use your fingers to press the mixture into an even layer on the bottom of the pan. Prick the shortbread crust with a fork and bake for 25-30 minutes until the edges start to brown and the shortbread crust is baked through.

Creamy Lemon Bar Filling

  • While the crust bakes, whisk together the eggs and sugar in a small bowl. Add the sourdough discard and whisk completely until smooth. This is an important step – the sourdough discard should be completely broken down and incorporated before adding the rest of the ingredients. Zest in a lemon and pour in the freshly squeezed lemon juice. Whisk to combine. Pour in the milk and whisk.
  • As soon as the shortbread crust comes out of the oven, pour the lemon bar filling over the top of the bars. It is normal for this filling to be very liquidy when you pour it in. Don't panic! Bake the bars for 30-35 minutes until the middle of the bars is set with no jiggles or wobbles in the middle.
  • Let bars cool for about 1 hour at room temperature. Then place the entire pan of bars into the refrigerator to chill for about 2 hours or overnight. Once bars are chilled, they can be sliced into squares and dusted with powdered sugar – right before serving. Enjoy!

Notes

Sourdough Discard: This lemon bar recipe is unique in that it uses only sourdough discard (no flour or cornstarch) in the filling and uses sourdough discard in the crust. Use a discard that is young and fresh. Do not use one that is not overly sour or has been sitting in the fridge for a long time. 
Store leftover lemon bars in the refrigerator in an air-tight container for up to a week. They can also be frozen and stored in the freezer for up to 3 months.
Keyword sourdough discard lemon bars, sourdough lemon bars
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6 Comments

  1. Crust thick so took 10 extra minutes to bake but great lemon tartness. Powdered sugar should be LAST bcz does evaporate into chilled lemon. Will make again but maybe bit larger pan than 8×8.

    1. Thanks for sharing! I love a thicker crust, so if you want to make these in a larger pan with a thinner crust, that would work well too.