• Preheat an oven to 175°c/155°c fan (350°f/310°f).

  Grease & line an 8" square baking tin with baking parchment then set aside.
• Next, melt the white chocolate for the cheesecake then set to one side, to cool slightly.

  You can melt the chocolate in a microwave or over a bain marie! We're melting this first, so that it doesn't melt the cream cheese when we make the cheesecake layer.

Chocolate Brownie

• Roughly chop the dark chocolate & butter then place into a large heatproof bowl along with the sea salt. Set this over a pan of barely simmering water & cook until just melted, stirring regularly.
• Whilst your chocolate is melting, place the eggs & both sugars into the bowl of a stand mixer, with the whisk attached. Whisk on medium speed, until the eggs are pale, light & fluffy. This will take around 10 minutes.

  The whisk will leave a trail in the eggs when they are whisked enough.
• Once the chocolate is melted, take the bowl off the heat then whisk in the cocoa powder. Set aside to cool slightly whilst the eggs are whisking.
• When the eggs have finished whisking, turn the mixer's speed down slightly & slowly pour in the melted chocolate, mixing until just combined.
• Once all the chocolate has been incorporated, remove the bowl from the mixer & give the sides a good scrape down. Add in the flour & gently fold in until just combined.
• Pour the brownie batter into the lined tin, smoothing it into an even layer with a palette knife. Set this to one side.

White Chocolate Cheesecake

• Give your stand mixer's bowl a quick clean then add in the cream cheese, cooled white chocolate, caster sugar, egg, vanilla, lime zest & a pinch of salt. Mix with the paddle attachment until combined & smooth. This will take 2-3 minutes on a medium speed.
• Pour the cheesecake mix on top of the brownie then gently spread out into an even layer with a palette knife.

  Spread the cheesecake out gently, so that it doesn't mix in with the brownie layer!
• Bake the brownie in the preheated oven until the cheesecake layer is set, with a slight wobble. This will take 20-25 minutes.
• Once baked, let the brownie cool to room temperature then chill in the fridge for at least 2 hours.

Blackberry Cheesecake

• Add the blackberries into a small saucepan, along with the caster sugar & a pinch of salt. Set the pan over a medium-low heat then cook until the blackberries are soft & broken down. This will take 10 minutes or so.
• Give the blackberries a blitz with a stick blender (or a jug blender) then pass into a bowl, through a sieve. Leave to cool at room temperature then chill until cold.
• Next, add the mascarpone, icing sugar & vanilla paste into the bowl of a stand mixer. Whisk on a medium speed, until combined & smooth. This will only take a minute or two.
• Add the blackberry puree into the mascarpone then whisk on a medium-low speed, to combine. Then with the mixer still running, gradually pour in the double cream.
• Once all of the cream has been added, increase the mixer speed to medium & continue whisking until the mascarpone reaches soft peaks. This will take around 2-3 minutes of whisking.
• Spoon the blackberry cheesecake on top of the chilled brownie, spread into an even layer with a palette knife then refrigerate overnight, to set.

To Finish

• The next day, carefully lift the brownies out of the tin, discard the baking parchment then place onto a large chopping board.
• Using a sharp serrated knife, trim each of the 4 edges slightly then dust the top of the brownie with the cocoa powder.

  Trimming the brownies is optional but gives us neater portions. To make things easier, I like to run the knife under warm water then dry between each cut.
• Cut the brownie into 12 squares then serve at room temperature.