Make the peanut butter dough: In a bowl, beat the peanut butter, butter and brown sugar until light and fluffy. Beat in the egg and vanilla. In a separate bowl, whisk the flour, baking soda and salt. Gradually mix into the wet ingredients until just combined.
Make the brownie dough: Whisk together the melted butter and white sugar. Beat in the cocoa powder until smooth, then the egg and vanilla. Fold in the flour, baking powder, salt and chocolate chips until no dry streaks remain.
Chill both doughs for 30 minutes. Scoop 1-2 tbsp portions of each dough and place side by side on a parchment-lined baking sheet. Use a toothpick or skewer to gently swirl the doughs together in a marble pattern.
Bake at 350°F for 9-11 minutes, until the tops are lightly crackly and the edges are just set. The centers will still be quite soft.
Allow to cool on the baking sheet for 5-10 minutes before transferring to a wire rack to cool completely.
ADVERTISEMENT
