Chewy Sugar Cookie Bars with Sourdough Discard

These Sourdough Discard Sugar Cookie Bars are an easy, crowd-pleasing alternative to rolling and cutting individual cookies. They bake in a single 9×13 pan, frost smoothly, and can be decorated with any color of icing and your favorite sprinkles to suit birthdays, holidays, or everyday treats.

Prefer cut-out cookies? See the related recipe listings below for classic sourdough sugar cookies and lemon sugar cookies.

Why you’ll love this recipe

• Made in one pan — no rolling, cutting, or baking multiple batches.
• Uses sourdough discard for extra flavor; easily adaptable to active starter if you prefer.
• Highly customizable — color the frosting and add sprinkles to match any occasion.
• The dough only needs a short chill (about 30 minutes) so it’s quick to assemble.
• Great base for variations like lemon or funfetti cookie bars.

Ingredients

You only need a handful of common baking ingredients to make these cookie bars. Measure the flour and sourdough discard by weight when possible for best results.

• Sourdough discard: Use unfed discard brought to room temperature. This recipe assumes a 1:1 starter feeding ratio. If your starter is maintained at a different ratio, adjust as needed.
• Butter: Softened to room temperature so it creams properly with the sugar.
• Food coloring and sprinkles: Optional but an easy way to personalize the finished bars.

Full ingredient amounts are listed in the recipe card below.

Substitutions & Variations

This recipe adapts well to different preferences. A few helpful options:

• Active sourdough starter: Replace discard with 200 g active starter and omit any additional yeast. Expect slightly more rise and allow extra bake or rest time as needed.
• Funfetti-style: Stir ½ cup rainbow sprinkles into the dough for colorful interior speckles.
• Colorful icing: Tint the buttercream with gel or liquid food coloring to match themes or holidays.
• Citrus variation: For a bright twist, try a lemon-scented version by swapping some vanilla for lemon zest and a touch of lemon juice.

How to Make Sourdough Discard Sugar Cookie Bars

The process is straightforward: combine dry ingredients, cream butter and sugar, mix in the discard and egg, bring everything together into dough, chill briefly, press into a pan, bake, and frost.

1. Step 1: Whisk together the all-purpose flour, kosher salt, and baking powder in a medium bowl and set aside.

2. Step 2: In a large bowl, cream the softened butter and granulated sugar until light and fluffy, about 2–3 minutes.

3. Step 3: Mix in the sourdough discard, egg, and vanilla extract until combined.

4. Step 4: Fold the dry ingredients into the wet mixture until a smooth dough forms. Cover and chill in the refrigerator for 30 minutes to make it easier to press into the pan.

5. Step 5: Scoop portions of dough into a lined or greased 9×13-inch baking pan.

6. Step 6: Press the dough evenly to the edges of the pan, filling any gaps so the surface is relatively smooth before baking.

7. Step 7: Bake at 350°F for about 25–30 minutes, until the edges are lightly golden. The top won’t spread much as it bakes.

8. Step 8: Cool completely on a wire rack before frosting to prevent the icing from melting.

9. Step 9: Make a simple buttercream by creaming softened butter, then gradually adding confectioner’s sugar, vanilla, and 3–4 tablespoons milk until smooth. Tint with food coloring if desired.

10. Step 10: Spread the frosting over the cooled bars, add sprinkles if you like, slice into portions, and serve.

Expert Baking Tips

• Weigh flour and discard: Use a kitchen scale when measuring flour and sourdough discard for consistent results.
• Butter temperature matters: Make sure the butter is softened to room temperature to cream properly with the sugar.
• Chill the dough: Refrigerate for at least 30 minutes (or up to 2 days) to make shaping and pressing easier.
• Cool completely before frosting: Warm bars will cause the frosting to slide off or melt, so allow them to cool fully.
• Try related recipes: This base works well for Lofthouse-style cookies, chocolate chip bars, or lemon cookie bars when you change flavorings and mix-ins.

Storage

Room temperature: Store finished cookie bars in an airtight container for 5–6 days.

Freezer: Freeze in a freezer-safe container or bag for up to 3 months. Thaw to room temperature before serving.

Recipe FAQs

More Sourdough Discard Cookie Recipes

If you make these Sourdough Discard Sugar Cookie Bars, please leave a star rating and a comment to let the author know how they turned out. Happy baking!

Sourdough Discard Sugar Cookie Bars

A simple, customizable sugar cookie bar made with sourdough discard. Frost and decorate to match any celebration.

Equipment

• Kitchen scale (recommended)
• Hand-held mixer or stand mixer
• 9×13-inch baking pan
• Parchment paper (optional)

Ingredients

For the Cookies

• 2 2/3 cups all-purpose flour
• 1/2 teaspoon kosher salt
• 1/2 teaspoon baking powder
• 14 Tablespoons unsalted butter, softened
• 1 cup granulated sugar
• 200 grams (about 3/4 cup) sourdough discard, unfed and at room temperature
• 1 egg
• 2 teaspoons vanilla extract

For the Frosting

• 3/4 cup unsalted butter, softened
• 2 2/3 cups confectioner’s sugar
• 1 1/2 teaspoons vanilla extract
• 3–4 Tablespoons milk (dairy or non-dairy)
• Food coloring (optional)
• Sprinkles (optional)

Instructions

1. In a medium bowl, whisk together flour, salt, and baking powder. Set aside.
2. In a large bowl, beat butter and granulated sugar until light and fluffy, about 2–3 minutes.
3. Add sourdough discard, egg, and vanilla extract to the creamed butter and mix until combined.
4. Fold the dry ingredients into the wet ingredients until a smooth dough forms. Cover and chill for 30 minutes (or up to 2 days).
5. Preheat oven to 350°F. Line a 9×13-inch pan with parchment if desired.
6. Scoop dough into the pan and press evenly to the edges so the surface is relatively smooth. The dough will not spread much during baking.
7. Bake 25–30 minutes until the edges are lightly golden. Cool in the pan for 10 minutes, then transfer to a rack to cool completely.
8. Make the frosting: cream the butter until light, then gradually add confectioner’s sugar. Add vanilla and start with 3 Tablespoons milk, adding more if needed for spreadable consistency. Tint with food coloring if desired.
9. Spread frosting over cooled bars, add sprinkles, cut into 20 pieces, and serve.

Notes

One cookie bar equals one serving. This recipe can be made with active sourdough starter: substitute 200 g active starter for the discard; no other ingredient changes required. Expect slightly more rise when using active starter.

Nutrition (per serving)

Calories: 176 kcal; Carbohydrates: 41 g; Protein: 2 g; Fat: 7 g; Sugar: 10 g.