Add in the Greek yoghurt, egg, vanilla and icing sugar until smooth and creamy.
Stir through the broken pieces of Oreos and then place in the fridge while you make the brownies.
Brownies;
Preheat the oven to 180°C (350°F) and line a 9'' baking tin with baking paper.
Melt the butter and dark chocolate together.
Mix the eggs, sugar, brown sugar and vanilla extract together until the mixture becomes a light golden colour.
Mix in the chocolate mixture.
Stir in the flour and cocoa until just combined.
Spread half of the brownie mixture into an even layer.
Top with the cookies and cream cheesecake mixture.
Top with the remaining brownie mixture and place in the oven for 30-35 minutes. The top and sides should be set and crackled. The middle will be slightly wobbly.
If you are adding extra broken pieces of Oreos, add them to the top of the hot brownies. Allow the brownies to cool before serving or chill completely in the fridge and then serve.
Store in an airtight container in the fridge for up to a week.