Line an 8inch/20cm square tin with greaseproof baking paper
In a large bowl, cream together the butter with the sugars for 2-3 mins using a stand mixer or electric whisk
Add the egg and vanilla extract and beat again until combined
In a separate bowl mix together the flour, baking powder, bicarbonate of soda and salt
Once the dry ingredients are mixed, add these into the butter and sugar mixture. Mix until combined
Add the chocolate chips and mix until evenly distributed
Pop the cookie dough into the bottom of your prepared tin, making sure its level and goes right up to the edges
Randomly place the Oreo bites on top, slightly pressing them into the cookie dough
Chill the cookie dough for 30 mins in the fridge
Preheat the oven to 200°C/180°C fan
Break up the chocolate into a microwave safe bowl
Melt the chocolate together with the butter in the microwave in 30 second intervals, stirring in between until the chocolate has melted. Set aside
In a separate bowl, whisk the eggs and caster sugar together for 2 mins. The mixture should turn paler in colour
Add the melted chocolate and butter mixture, along with the vanilla and combine
Sieve the flour into the mixture and fold in
Add the mixture on top of the cookie layer, covering the Oreo bites
Break up the brownie flavoured Oreos and scatter them over the top of the brownie mixture
Bake for approx. 25 mins. You will want the brookie to have a slight wobble and to have just started to crack around the edges
Leave the brookie to cool in the tin for at least 4 hours, ideally overnight
Slice up into 12 portions and enjoy
