1. Preheat the oven to 170
  2. Cream the butter and sugar together
  3. Add the eggs, espresso and vanilla and mix
  4. Fold in the cacao and oats
  5. Transfer the mixture to a lined baking tray
  6. Dollop the PB on top of the brownie and swirl with a knife.
  7. Bake for approx. 30 minutes or until set