Cookie layer

1. Line an 8inch/20cm square tin with greaseproof baking paper

2. In a large bowl, cream together the butter with the sugars for 2-3 mins using a stand mixer or electric whisk

3. Add the egg and vanilla extract and beat again until combined

4. In a separate bowl mix together the flour, baking powder, bicarbonate of soda and salt

5. Once the dry ingredients are mixed, add these into the butter and sugar mixture. Mix until combined

6. Add the chocolate chips and mix until evenly distributed

7. Pop the cookie dough into the bottom of your prepared tin, making sure its level and goes right up to the edges

8. Randomly place the Oreo bites on top, slightly pressing them into the cookie dough

9. Chill the cookie dough for 30 mins in the fridge

Brownie Layer

1. Preheat the oven to 200°C/180°C fan

2. Break up the chocolate into a microwave safe bowl

3. Melt the chocolate together with the butter in the microwave in 30 second intervals, stirring in between until the chocolate has melted. Set aside

4. In a separate bowl, whisk the eggs and caster sugar together for 2 mins. The mixture should turn paler in colour

5. Add the melted chocolate and butter mixture, along with the vanilla and combine

6. Sieve the flour into the mixture and fold in

7. Add the mixture on top of the cookie layer, covering the Oreo bites

8. Break up the brownie flavoured Oreos and scatter them over the top of the brownie mixture

9. 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

10. Leave the brookie to cool in the tin for at least 4 hours, ideally overnight

11. Slice up into 12 portions and enjoy