Ingredients:

  • 1/2 cup (113g) unsalted butter, melted
  • 1 cup (200g) packed light brown sugar
  • 1 large egg
  • 2 teaspoons vanilla extract
  • 1/4 teaspoon salt
  • 1 cup (120g) all-purpose flour
  • 1/2 cup (60g) chopped walnuts or pecans (optional)
  • 2 tablespoons (28g) unsalted butter, softened
  • 1/4 cup (50g) granulated sugar
  • 2 teaspoons ground cinnamon

Instructions:

  1. Preheat oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper, leaving an overhang for easy removal.
  2. In a large mixing bowl, combine melted butter and brown sugar. Whisk until smooth and well combined.
  3. Whisk in the egg and vanilla extract until fully incorporated.
  4. Gradually add the salt and all-purpose flour to the wet ingredients, mixing until just combined. Be careful not to overmix. Gently fold in nuts, if using.
  5. In a separate small bowl, combine softened butter, granulated sugar, and cinnamon. Mix until a paste forms.
  6. Pour half of the blondie batter into the prepared baking pan. Dot spoonfuls of the cinnamon sugar mixture over the batter. Pour the remaining blondie batter on top.
  7. Use a knife or skewer to gently swirl the cinnamon sugar mixture into the blondie batter. Don't over-swirl; a little streaking is perfect.
  8. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached.
  9. Let cool completely in the pan before lifting out using the parchment paper overhang.
  10. Cut into squares and serve.