Ingredients:

  • ½ cup (1 stick / 113g) unsalted butter, melted
  • 1 cup (200g) granulated sugar
  • 2 large eggs
  • 1 teaspoon (5ml) vanilla extract
  • ⅓ cup (30g) unsweetened cocoa powder
  • ½ cup (60g) all-purpose flour
  • ¼ teaspoon (1.5g) salt
  • ¼ teaspoon (1g) baking powder
  • ½ cup (128g) creamy peanut butter
  • 12-16 mini peanut butter cups (or 6 regular-sized, chopped)
  • ½ cup (85g) chocolate chips (semi-sweet or dark) (optional)

Instructions:

  1. Preheat oven to 350°F (175°C). Line a 9x9 inch baking pan with parchment paper or grease well.
  2. In a large bowl, whisk melted butter and sugar until smooth.
  3. Add eggs and vanilla; mix until well combined.
  4. In the same bowl, stir in cocoa powder, flour, salt, and baking powder until just combined – be careful not to overmix.
  5. Pour half the batter into the prepared pan and spread evenly.
  6. Gently warm peanut butter in the microwave for 10-15 seconds until easily drizzled. Drizzle half the peanut butter over the batter.
  7. Press peanut butter cups evenly into the batter.
  8. Pour remaining batter over the top, and smooth evenly.
  9. Drizzle remaining peanut butter on top. Use a knife or skewer to swirl the peanut butter into the top layer.
  10. Bake for 30-35 minutes. Check doneness with a toothpick – it should come out with a few moist crumbs attached.
  11. Let cool completely in the pan before cutting into squares.