Ingredients:

  • 225cup unsalted butter
  • 300cup light brown sugar, packed
  • large egg, room temperature
  • large egg yolk, room temperature
  • pure vanilla extract
  • 250cup all-purpose flour
  • sea salt
  • baking powder
  • 190cup fresh blueberries
  • cornstarch
  • lemon zest

Instructions:

  1. Melt the butter in a light-colored saucepan over medium heat. Whisk constantly as it foams. Once brown specks appear and it smells nutty, remove from heat immediately and pour into a large bowl to cool for 5 minutes.
  2. Whisk the brown sugar into the warm brown butter. Add the egg, egg yolk, and vanilla extract. Whisk vigorously for 1-2 minutes until the mixture is glossy and lightened in color.
  3. Sift the flour, sea salt, and baking powder into the wet ingredients. Use a spatula to gently fold the mixture until just combined.
  4. In a small bowl, toss the blueberries with cornstarch and lemon zest to prevent bleeding. Gently fold the blueberries into the blondie batter.
  5. Spread the batter into a parchment-lined 8x8 inch metal baking pan. Bake at 350°F (175°C) for 35 minutes or until the edges are golden and the top is crackly. Let cool completely before slicing.