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Several frosted sourdough sugar cookie bars are displayed on a surface. Each bar has a layer of pink frosting topped with colorful sprinkles. One bar is propped up to show its layers.

Frosted Sourdough Sugar Cookie Bars

Elien Lewis
Soft, buttery, and topped with a thick layer of buttercream, sourdough sugar cookie bars are a fun and easy way to use up extra sourdough discard. They have that perfect chewy sugar cookie flavor and texture but in bar form. No rolling or cutting needed!
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Prep Time 12 minutes
Cook Time 28 minutes
2 hours
Total Time 2 hours 40 minutes
Course Dessert
Cuisine American
Servings 16
Calories 211 kcal

Ingredients
 
 

  • 113 g butter softened to room temperature
  • 150 g granulated sugar
  • 1 large egg yolk
  • 50 g sourdough discard starter
  • 1.5 teaspoons vanilla paste or extract
  • 156 g all-purpose flour
  • 3/4 teaspoon baking powder
  • 1/4 teaspoon salt

Buttercream

  • 85 g butter softened to room temperature
  • 180 g powdered sugar
  • 1-2 tablespoon heavy cream room temperature
  • 1 teaspoon vanilla paste Or extract
  • 1/8 teaspoon salt omit if using salted butter
  • Pink food color and sprinkles optional

Instructions
 

  • Line an 8x8-inch (20x20cm) baking pan with parchment paper, leaving an overhang so you can easily lift out the baked bar.
  • In a large bowl, beat butter and sugar until fluffy, about 2-3 minutes with an electric mixer. Mix in sourdough discard, eggs, and vanilla until smooth.
  • In a small seperate bowl, whisk together flour, baking powder, and salt. Add this to the butter mixture and mix until just combined.
  • Spread dough evenly into the prepared pan. The dough can be a bit sticky, so I place little pieces of dough all over the pan and then use my fingers to press it together. Then chill for 2 hours or up to 36 hours.
  • When ready to bake, heat the oven to 180°C (350°F).
  • Bake for 25-28 minutes until lightly golden brown and the top is set. Let cool completely.

Buttercream

  • In a bowl add the butter and powdered sugar. Starting on low, with an electric beat the butter and powdered sugar until combined. Add vanilla, and cream and beat on high speed until smooth and creamy and light. Add in food color if you like.
  • Spread frosting over cooled bars and add sprinkles.
  • Cut into 16 bars. For extra smooth cuts, chill the cookie slab in the fridge for an hour first to firm up the frosting.

Notes

Storing & Freezing

  • Store at room temp in an airtight container for up to 3 days or refrigerate for up to a week.
  • Freeze frosted or unfrosted bars for up to 2 months.

Nutrition

Serving: 1cookie barCalories: 211kcalCarbohydrates: 28gProtein: 1gFat: 11gSaturated Fat: 7gPolyunsaturated Fat: 0.5gMonounsaturated Fat: 3gTrans Fat: 0.4gCholesterol: 39mgSodium: 155mgPotassium: 16mgFiber: 0.3gSugar: 20gVitamin A: 338IUVitamin C: 0.01mgCalcium: 18mgIron: 1mg
Keyword cookie bars, Sourdough discard, Sugar cookies
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