These Sourdough Discard Lemon Cookie Bars are a perfect sweet treat when you don't want to spend time rolling, cutting, and baking multiple batches of cookies. They're packed with lemon flavor and topped with a lemon buttercream frosting. Looking for a little customization? You can easily customize these cookies with different colors of icing and sprinkles!
Looking for a traditional cut-out sugar cookie recipe? Try my Sourdough Discard Lemon Sugar Cookies and these Sourdough Discard Sugar Cookies.
Why you'll love this recipe
- Sourdough Discard Lemon Sugar Cookie Bars are light, bright, and full of lemon flavor! The lemon buttercream frosting adds a zesty sweetness to the cookie.
- These lemon cookie bars are made with sourdough discard, but you could easily modify to use active sourdough starter, if you prefer.
- These cookie bars are made in one batch - no need to bake multiple batches of cookies!
- This recipe uses lemon juice and lemon zest for flavor; no lemon extract needed.
- These cookies only need to chill for 30 minutes (to make the dough easier to handle when pressing into the pan).
- Looking for other cookie bar recipes? Try these Sourdough Chocolate Chip Cookie Bars and these Sourdough Discard Sugar Cookie Bars.
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Ingredients
There are only a few key ingredients you need to bring these lemon cookie bars together.
- Sourdough discard: The sourdough discard should be unfed and at room temperature for this recipe. This recipe is designed for a sourdough starter with a 1:1 ratio (when you feed your starter, it's with 1 part flour and 1 part water). If your starter uses a different ratio, you may need to adjust some of the ingredients in this recipe.
- Learn more about how to make a sourdough starter.
- Lemon juice and lemon zest: This is where the cookies and the frosting get their lemon flavor. Don't skimp on the juice or zest!
See full recipe below for detailed directions.
Substitutions & Variations
This is a very adaptable recipe and below are a few easy substitutions and variations you can try.
- Use active sourdough starter - If you'd like to make this recipe with active sourdough starter, you can! To do so, omit the yeast and replace the sourdough discard with active starter (200g). You will also need to increase the rise times.
- Use oranges instead of lemons - These cookies would also be delicious using orange juice and orange zest rather than lemon!
- Customize your colors and sprinkles - Food coloring is another easy way to customize these cookies. The icing is typically white, but could be any color, and you can add sprinkles to make these as festive as you like!
How to Make Sourdough Discard Lemon Cookie Bars
There are only a few key steps to bring this recipe together. The full recipe with detailed directions is at the bottom of this post.
- Step 1: Mix together the flour, salt, and baking soda.
- Step 2: Cream together the butter and sugar until light and fluffy.
- Step 3: Add the remaining wet ingredients, then add the dry ingredients. Mix until a smooth dough forms. Cover and let chill for 30 minutes (or up to 2 days).
- Step 4: Scoop the cookie dough into a 9x13-inch baking pan.
- Step 5: Press the cookie dough to the edges of the pan and fill any spaces.
- Step 6: Bake until lightly golden on the edges. Let the cookie bar cool completely.
- Step 7: Mix together the buttercream frosting while the cookies cool.
- Step 8: Spread the cookie with the frosting, top with lemon zest, and sprinkles (optional). Slice and enjoy!
Expert Baking Tips
- Use metric measurements for at least the flour and sourdough discard. These are two ingredients where there can be a huge variation in using cups vs. metric measurements. Using a kitchen scale for metric measurements for at least these two ingredients will set you on the right path!
- Make sure your butter is softened to room temperature. This will ensure that it creams together appropriately with the sugar.
- Let the dough chill for at least 30 minutes (or up to 2 days) to make it easier to press into the baking pan.
- Let the cookie bars cool completely before adding the frosting, otherwise it will melt right off.
- Looking for other cookie recipes? Try these Sourdough Lofthouse Cookies and these Sourdough Discard Chocolate Chip Cookies.
Storage
Room Temperature Storage: Store cookie bars in an airtight container at room temperature for up to 5-6 days.
Freezer Storage: Store cookie bars in a freezer-safe container or bag and freeze for up to 3 months. Before serving, let the cookies thaw to room temperature.
Recipe FAQs
They're accurate! I use the metric measurements for my own baking, especially with the flour and sourdough discard, so I recommend you do the same! There can be such a huge variation in cups measurements, particularly for those two ingredients.
Make sure your butter is softened to room temperature (I like to leave it out on the kitchen counter overnight if I know I'll need softened butter the next day). Cream the butter for 2-3 minutes, then add the powdered sugar and mix. Use room temperature milk and lemon juice and mix that in thoroughly until smooth!
Buttercream is also best if you use it right away. If you let it sit, and then frost, it will start to get chunky (still delicious, though)!
More Sourdough Discard Cookie Recipes
If you tried these Sourdough Discard Lemon Cookie Bars or any other recipe on my website, please leave a ⭐ star rating and let me know how it went in the comments below. I'd love to hear from you! Happy Baking!
Sourdough Discard Lemon Cookie Bars
Equipment
- Parchment paper optional
Ingredients
For the Cookies
- 2 ¾ cup all-purpose flour
- ½ teaspoon kosher salt
- ¼ teaspoon baking soda
- 14 Tablespoons unsalted butter softened
- 1 cup granulated sugar
- 200 grams (about ¾ cup) sourdough discard unfed, at room temperature
- 1 egg
- 3 Tablespoons lemon zest
- 1 Tablespoon lemon juice
- 2 teaspoons vanilla extract
For the Frosting
- ¾ cup unsalted butter softened
- 2 ⅔ cup confectioner's sugar
- 1 ½ Tablespoons lemon juice
- 1 ½ Tablespoons milk non-dairy or regular dairy
- lemon zest for topping
- sprinkles optional
Instructions
- Make the cookies. In a medium bowl, mix together the flour, salt, and baking soda. Set aside.
- In a large bowl using a hand-held mixer, beat together the butter and sugar until light and fluffy, about 2-3 minutes. Add the sourdough discard, egg, lemon zest, lemon juice, and vanilla extract. Mix until combined.
- Add the dry ingredients to the wet ingredients and mix until combined, and a smooth dough forms. Cover the mixing bowl with plastic wrap. Chill in the refrigerator for 30 minutes (or up to 2 days).
- Preheat the oven to 350℉ and line a 9x13-inch baking pan with parchment paper (optional, but it makes it easier to get the baked bars out of the pan).
- Using a large cookie scoop or spoon, roughly scoop the cookie dough into the baking pan. Use your hands or a spatula to evenly press the cookie dough to the edges of the pan and fill any spaces.The dough will not spread much, so you want this to be pressed fairly flat and even. We will cover it with frosting, too, so don't worry too much!
- Bake for 25-30 minutes until lightly browned at the edges. Let cool in the baking pan for at least 10 minutes, then transfer to a cooling rack to cool fully.
- Make the frosting. Once the cookie bars are fully cooled, cream the butter in a medium-sized bowl until light and fluffy, 2-3 minutes, then slowly mix in the confectioner's sugar. Add the lemon juice and milk, mixing until fully smooth and incorporated. Add more milk if you feel that the frosting is too thick.If using food coloring, add a few drops and mix until you reach your desired color.
- Spread the cooled cookie bars with a layer of frosting, sprinkle with lemon zest, and add sprinkles (optional). Cut into 20 pieces, and serve!
Jessica Vogl says
Loveeee the lemon flavor, and the lemon buttercream frosting is just *chef's kiss*!