Preheat oven to 180°C. Grease a large square baking pan and line with baking paper.
Sift cocoa and flour into a large bowl, add sugar and stir until combined.
In a separate bowl, beat eggs, Chocolate Essence and Vanilla Bean Paste. Add egg mixture and cooled melted butter to flour mixture. Combine with a wooden spoon the press into prepared baking pan.
Melt peanut butter in a microwave safe bowl for 10-15 seconds. Stir until smooth. Spread over top of brownie mixture and swirl to combine. Top with choc chips and bake for 30 minutes. Brownies are done when the centre of cake no longer wobbles (brownies are traditionally dense and fudge like – a skewer will not come out clean).
Allow to cool completely, then cut into squares to serve. For a real indulgence serve warmed with a scoop of ice cream.