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5 from 4 votes

Sourdough Blondies with Chocolate Chunks

These sourdough blondies are the ultimate dessert bar! The addition of sourdough starter makes these chocolate chunk blondies tender and moist. The classic flavors of brown sugar and vanilla are complimented by the addition of flaky sea salt.
Prep Time10 mins
Cook Time40 mins
Total Time50 mins
Course: Dessert
Cuisine: American
Keyword: blondies, chocolate chunk blondies, sourdough blondies, sourdough starter
Servings: 24 servings
Calories: 333kcal


  • Mixing Bowls
  • Hand Mixer
  • 9x13 baking pan


  • 20 tablespoon unsalted butter
  • 3 cups flour
  • ¼ teaspoon baking powder
  • 1 teaspoon flaky sea salt such as Maldon, plus more, for serving
  • 1 teaspoon kosher salt
  • 2 ¼ cups dark brown sugar
  • 2 eggs straight from the fridge
  • 1 tablespoon vanilla extract
  • ½ cup sourdough starter
  • 2 ½ cups chocolate chunks divided


  • Brown the butter about an hour before making the dough. You can find an entire step-by-step guide on how to brown butter here.
  • When ready to bake, preheat the oven to 325 degrees. Lightly coat a 9x13 light metal pan with baking spray, place a large piece of parchment paper longwise across the pan so that a few inches of paper hang over the edges, like handles. You can secure the edges of the paper with metal clips, if desired.
  • In a medium bowl, whisk together the flour, baking powder, 1 teaspoon of the flaky salt, and kosher salt and set aside.
  • In a large bowl, combine the dark brown sugar and eggs with a hand mixer on medium until smooth. Add the vanilla and sourdough starter, mixing again to combine. Scrape down the bowl before adding the cooled browned butter. Mix until thick and glossy, about a minute more.
  • Add the dry ingredients and 2 cups of the chocolate chunks to the wet ingredients. Stir with a study wooden spoon or rubber spatula, until just combined and no dry streaks of flour remain.
  • Spread batter into prepared pan and sprinkle with remaining chocolate chunks. Bake in preheated oven for 40 – 45 minutes, or until edges are risen and begin to pull away from the pan and the top of the blondies are deeply golden, shiny, and krinkly.
  • Remove from oven and immediately sprinkle with a generous dose of more flaky sea salt, if desired.
  • Cool bars completely on wire rack before slicing and serving.



Recipe adapted from Shauna Sever's Midwest Made.
Bars can be stored in a sealed, air-tight container for up to a week.


Serving: 1square | Calories: 333kcal | Carbohydrates: 43g | Protein: 3g | Fat: 17g | Saturated Fat: 10g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 5g | Trans Fat: 1g | Cholesterol: 40mg | Sodium: 179mg | Potassium: 153mg | Fiber: 2g | Sugar: 27g | Vitamin A: 320IU | Calcium: 38mg | Iron: 2mg