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Sourdough Peanut Butter Blondies

Sourdough Peanut Butter Blondies

If peanut butter is a whole food group in your house like it is in mine, you need these Sourdough Peanut Butter Blondies. They're thick, chewy, loaded with peanut butter, and stuffed with chunks of Reese's peanut butter cups. Perfect for any time you need a decadent dessert!
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Prep Time 25 minutes
Cook Time 30 minutes
Servings 9

Equipment

  • 9×9-inch baking pan - to bake your blondies. I love this pan 9x9 pan from USA Bakeware.Parchment paper- to line your pan for easy removal.
  • Mixing bowls - to mix the blondie batter, chocolate ganache, and peanut butter drizzle.
  • Whisk - to mix ingredients.
  • Spatula - to spread the the batter.
  • Digital kitchen scale (optional) - for accurate measuring, especially helpful with sourdough baking. I linked the one I like here.
  • Measuring cups and spoons - for measuring ingredients.
  • Oven safe metal clips (optional) - for holding the parchment down to the pan. I love these metal clips that are heat safe and keep my parchment from sliding around.
  • Ziplock or pastry bag (optional) - for the peanut butter drizzle.
  • Toothpick or skewer - for the peanut butter swirl design.

Ingredients
  

Peanut Butter Blondies:

  • 1/2 (113g) cup unsalted butter melted
  • 2/3 (160g) cup creamy peanut butter Skippy or Jiff
  • 1 (200g) cup granulated white sugar
  • 3/4 (150g) cup packed light brown sugar
  • 1/2 (120g) cup sourdough discard
  • 2 eggs
  • 1 egg yolk
  • 2 tsp vanilla extract
  • 1 tsp cornstarch
  • 1 1/3 (175g) cups all-purpose flour
  • 1 1/2 tsp fine sea salt

Sourdough Discard Swap:

  • 1/4 (60g) cup whole milk
  • 1/4 (30g) cup all-purpose flour

Reese’s Center:

  • 8-9 snack size Reese’s Peanut Butter Cups roughly chopped

Chocolate Ganache:

  • 3/4 (180g) cup semi-sweet chocolate chips
  • 3 (42g) Tbsp unsalted butter melted
  • 6 (90g) Tbsp heavy cream
  • 3/4 tsp vanilla extract
  • 1/8 tsp fine sea salt

Peanut Butter Swirl:

  • 1/4 (70g) cup creamy peanut butter
  • 2 (10g) tsp salted butter melted

Toppings:

  • 3 Reese’s Peanut Butter Cups chopped
  • Flaky sea salt

Instructions
 

Step 1: Mix the Batter

  • Preheat your oven to 350°F (175°C). Line a 9x9 metal pan with parchment paper, leaving some overhang so the blondies are easy to lift out after chilling. I like to use metal clips to hold my parchment in place. Lightly spray with cooking oil.
  • In a medium saucepan or microwave-safe bowl, melt the butter and peanut butter until just melted. Whisk until smooth and creamy.
    1/2 (113g) cup unsalted butter, 2/3 (160g) cup creamy peanut butter
  • Whisk in the granulated sugar, brown sugar, sourdough discard, eggs, egg yolk, and vanilla extract until the blondie batter is shiny and smooth.
    1 (200g) cup granulated white sugar, 3/4 (150g) cup packed light brown sugar, 1/2 (120g) cup sourdough discard, 2 eggs, 1 egg yolk, 2 tsp vanilla extract
  • Add the flour, cornstarch, and salt to the blondie batter, and mix just until no streaks remain. Try not to overmix at this point or the blondies will be tough. You just want the flour incorporated.
    1 tsp cornstarch, 1 1/3 (175g) cups all-purpose flour, 1 1/2 tsp fine sea salt
  • Sourdough Discard Swap Option: If you don't have sourdough discard, add the extra flour and milk at this time and mix it into the blondie batter.
    1/4 (60g) cup whole milk, 1/4 (30g) cup all-purpose flour
  • Chop up 9 of the snack size Reese's cups up into large chunks (don't make them too small or they'll melt into the blondie).
    8-9 snack size Reese’s Peanut Butter Cups
  • Layer half of the blondie batter into the prepared pan, spreading the batter to the edges of the pan.
  • Sprinkle the chopped Reese's over the top of the blondie batter evenly.
  • Scoop the remaining blondie batter on top of the Reese's layer, and gently spread the batter to cover the Reese's to the edges of the pan. If they aren't entirely covered that's perfectly fine.
  • Overnight Fermentation Option: If you want to ferment this brownie batter, cover with plastic and refrigerate overnight in the pan. When you're ready to bake your brownie, allow to rest at room temperature for about an hour to warm up then bake as instructed.

Step 2: Bake the Blondies

  • Transfer the blondies to the hot oven, and bake at 350°F for 30-35 minutes, or until the edges are set, the center no longer jiggles, and a toothpick inserted in the center comes out with a little wet batter
  • Do not bake until the toothpick comes out completely clean. These blondies are meant to be fudgy and will continue to set as they cool. Baking time my vary on your oven, my brownies are done anywhere between 30-35 minutes. If you overbake these, they'll get bready and ruin the texture.
  • Cool the blondies completely in the pan before frosting.
  • For the cleanest blondie texture, you can refrigerate the cooled brownie for 30–60 minutes before frosting.
  • Blondies fresh out of the oven

Step 3: Frost the Blondies

  • While the blondie cools, prepare the chocolate frosting.
  • In a microwave safe bowl, heat the cream in the microwave or a small pot until steaming.
    6 (90g) Tbsp heavy cream
  • In another heat safe bowl, add the chocolate chips, butter, vanilla, and salt.
    3/4 (180g) cup semi-sweet chocolate chips, 3 (42g) Tbsp unsalted butter, 3/4 tsp vanilla extract, 1/8 tsp fine sea salt
  • Pour the hot cream over the chocolate chip mixture, and cover for five minutes.
  • After the frosting has rested, stir with a whisk until it's smooth, creamy, and glossy. If the chocolate hasn't fully melted microwave for 15 second intervals and stir until the frosting is smooth.
  • Once the blondies are completely cooled, pour the ganache on top of the brownies and spread it evenly over the brownies to the edge.
  • In a small bowl, add the peanut butter and butter. Microwave for 30 seconds, and whisk until smooth and runny.
    1/4 (70g) cup creamy peanut butter, 2 (10g) tsp salted butter
  • Transfer the peanut butter mixture to a Ziplock or pastry bag, and snip off 1/8 inch off of the end.
  • Pipe even lines about 1 inch apart diagonally across the chocolate ganache. Using a toothpick or skewer, draw lines in a zig zag motion vertically the opposite direction to create the peanut butter swirl effect. See the main blog for photos on how to do this.
  • Top the blondies with 3 more chopped Reese's cups scattered about and flaky sea salt if desired.
    3 Reese’s Peanut Butter Cups, Flaky sea salt
  • Transfer the pan to the refrigerator and chill for at least 2 hours, or until the frosting is set. I prefer to allow the brownie to chill overnight for it to set up cleanly and for the easiest cuts.
  • Condensation Note: If you chill the blondies overnight, make sure to cover them with plastic. Typically condensation can form on the top of the frosting if you don't cover the pan. The condensation should stick to the plastic wrap overnight, and you can remove the plastic as soon as you remove the brownies from the refrigerator.
  • After the blondies have set up, remove from the refrigerator.
  • Use the parchment paper to lift the blondies out of the pan. Slice the blondies in thirds both ways, to create 9 bars (or you can cut 12 for smaller sizes).
  • For the cleanest cuts, wipe the knife with a hot wet paper towel between slices. Enjoy!
  • Yields 9 blondies or 12 smaller blondies

Notes

How to Store:
Room Temperature- Store in an airtight container up to 3 days. Be careful about these blondies sitting in a warm environment, the frosting can melt.
Refrigerator- Keeps up to 5 days in an airtight container in the refrigerator. For the best texture, let them sit at room temperature for 10–15 minutes before serving.
Freezer- You can freeze the unfrosted blondies by wrapping them tightly and freezing for up to 2 months. Thaw in the refrigerator overnight, then frost as directed. Chill and enjoy!

Nutrition

Serving: 1barCalories: 700kcalCarbohydrates: 75gProtein: 11gFat: 42g
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