A good sugar cookie ranks among my favorite treats, but when I don’t feel like rolling and cutting cookies, I turn to these Sourdough Sugar Cookie Bars. They capture the same sweet, buttery flavor as traditional sourdough sugar cookies in an easy tray-bake format.
These bars are thick, chewy, and vanilla-forward, finished with a light layer of American buttercream—the same frosting I use on my Sourdough Vanilla Cupcakes—and cut into squares to feed a crowd. Add sprinkles for a festive touch. If you want a chocolate option, try the fudgy sourdough brownies.
Why You’ll Love Sourdough Sugar Cookie Bars
- Soft & Chewy: These bars have a tender, chewy texture that’s irresistibly satisfying.
- Crowd Pleaser: They’re easy to slice and serve, perfect for parties or potlucks.
- Uses Up Discard: Sourdough discard adds moisture and a subtle depth of flavor, making this an excellent way to use leftover starter.
Important Ingredients
- Sourdough Discard – Use discard that’s fresh or only a day or two old if you want minimal tang. Older discard will increase the sour flavor.
- Unsalted Butter – Unsalted butter gives you better control over the final flavor; adjust added salt if you use salted butter.
- Vanilla – Pure vanilla extract is great, and vanilla bean paste boosts the flavor even more.
- Buttercream Frosting – A simple American buttercream of butter, powdered sugar, heavy cream, vanilla, and a pinch of salt. Whip it until light and fluffy for the best texture.
See the recipe card below for full ingredient amounts and notes.
Substitutions
- Butter: If using salted butter, reduce added salt slightly. Unsalted gives the most consistent result.
- Vanilla: Vanilla bean paste is a great swap for extract. You can also use almond extract for a different, delicious flavor—try 1/2 to 1 teaspoon in the dough and 1/2 teaspoon in the frosting.
- Sourdough Discard: If you don’t have discard, you can substitute an active sourdough starter; adjust the flour slightly if your starter hydration differs.
How to Make Sourdough Sugar Cookie Bars
Mix and Bake Sugar Cookie Bars
Step 1: Cream butter and granulated sugar together until light and creamy, about 1 minute. Add the egg, sourdough discard, and vanilla, then beat until fully combined and fluffy.
Step 2: Whisk the dry ingredients—flour, baking powder, and salt—in a small bowl. Add them to the butter mixture and beat until a soft dough forms.
Step 3: Preheat the oven to 350°F. Line a 9 x 13 metal pan with parchment paper, then press the cookie dough evenly into the pan.
Step 4: Bake for about 35 minutes, until the edges are lightly browned and the center is set. Avoid over-browning the top to keep the bars tender. Cool completely before frosting.
Frost and Add Sprinkles
Step 5: Whip softened butter until creamy, then add powdered sugar, heavy cream, vanilla, and salt. Beat 3–4 minutes until light and fluffy, then spread on cooled bars.
Step 6: Add sprinkles if desired and cut into 24 bars for serving.
How to Store Leftovers
Store leftover bars in an airtight container in the refrigerator for a few days, or freeze them for longer storage. Thaw before serving or adding to a cookie tray.
Amy’s Recipe Tip
For an extra layer of flavor in the frosting, add a couple of tablespoons of sour cream while mixing—the tang pairs wonderfully with the sweet bars.
Frequently Asked Questions
Yes. Scoop dough into balls and refrigerate overnight or up to a couple of days before baking. Longer refrigeration increases sour flavor and brings more fermented flavor benefits.
They’re thick and chewy. For a thinner bar, reduce the recipe by roughly one-quarter.
Discard adds moisture and subtle complexity. Using younger discard keeps the flavor mild; older discard increases tang.
Yes. Halve the ingredients to fit an 8 x 8 pan for a smaller yield.
Cookie recipes you’ll Love
Lemon Crinkle Cookies With Sourdough Discard
Iced Oatmeal Sourdough Discard Cookies
Sourdough Pumpkin Cookies
Sourdough Chocolate Chip Cookie Bars
If you try these Sourdough Sugar Cookie Bars or another recipe from this site, leave a star rating and share how it went in the comments. Happy baking!
Sourdough Sugar Cookie Bars
Equipment
-
9 by 13 metal pan
-
parchment paper
-
hand mixer or stand mixer
Ingredients
Sourdough Sugar Cookie Bars
- 340 grams unsalted butter (about 1 1/2 cups)
- 450 grams granulated sugar (about 2 1/4 cups)
- 1 large egg (about 50 grams)
- 120 grams sourdough discard (about 1/2 cup)
- 10 grams vanilla extract (about 2 teaspoons)
- 480 grams all-purpose flour (about 3 2/3 cups)
- 8 grams baking powder (about 1 1/2 teaspoons)
- 10 grams salt (about 1 1/2 teaspoons)
Buttercream Frosting
- 113 grams unsalted butter (about 1/2 cup)
- 190 grams powdered sugar (about 1 1/2 cups)
- 25 grams heavy cream (about 1–2 tablespoons)
- 4 grams vanilla extract (about 1 teaspoon)
- 3 grams salt (about 1/2 teaspoon)
Sprinkles for finishing (optional)
Instructions
Sourdough Sugar Cookie Bars
- Preheat oven to 350ºF and line a 9 x 13 metal pan with parchment paper.
- Beat butter and granulated sugar until creamy, about 1 minute. Add the egg and sourdough discard and whip until well combined and light. Mix in vanilla.
- Whisk together flour, baking powder, and salt. Add the dry ingredients to the butter mixture and beat until a dough forms.
- Press dough into the lined pan in an even layer.
- Bake about 35 minutes, until edges are lightly browned and the center is set. Cool completely in the pan.
Sugar Cookie Frosting
- Whip softened butter until creamy. Add powdered sugar, heavy cream, vanilla, and salt. Beat 3–4 minutes until light and fluffy. Spread over cooled bars, add sprinkles if desired, and cut into 24 bars. Note: Add 1/2 teaspoon almond extract to the frosting for extra flavor. For a thicker frosting layer, double the frosting recipe.
Notes
Other Flavors: Try 1/2–1 teaspoon almond extract in the dough and 1/2 teaspoon in the frosting. You can also stir a tablespoon of sour cream into the frosting for a pleasing tang.
Nutrition
Nutrition information is automatically calculated and should be used as an approximation.