Preheat oven 200C | 390F. Spray a 9x9 inch baking pan with cooking spray and put aside.
Throw ALL ingredients (except chocolate chips and cups) into a food processor and blend until smooth (about 2 - 3 minutes).
Pour batter into prepared pan.
Spoon melted chocolate over batter, and with the back of a knife, gently swirl chocolate into and around batter.
Press pb cups into the batter
Bake for approx 20 - 25 minutes (depending on your oven) until a toothpick inserted into the centre comes out clean.
They are VERY moist when taken out, but they will set and firm as they cool! Don't over cook these - or they will become dry.
Once cooled, gently cut into 16 bars.