Start by pre-heating your oven to 180c/350f.

In a pot or pan, add the sugar and place this onto medium heat.

Keep heating this, whiles stirring, until all the sugar has melted and it is an amber colour.

Pour this into an 8 inch cake tin, then leave this aside to set at room temperature, this won't take long. Also side note DON'T grease this tin, the cake we are going to make rises better in an un-greased tin.

In a large bowl, add all the ingredients for the flan. Whisk these together.

Pour this through a sieve, then pour this into your tin, on top of the caramel layer. At this point the sugar will have set up. If it hasn't, wait until it does before pouring the flan mixture over it.

Leave this aside whiles you make the cake batter.

In a large clean bowl, add the egg whites and cream of tartar. Start whipping this.

Once they become foamy, slowly pour in the first 60g of sugar, whiles still whipping.

Once all the sugar has been added, whip until you get stiff peaks then leave this aside.

In a separate large bowl, add the egg yolks and the second 60g of sugar. Whip these just until the egg yolks lighten in colour and the mixture increases in volume slightly.

Add the oil, water and ube extract into this, whisk these in. Now add the flour and baking powder, whisk just until combined.

Add half of the whipped egg whites into this, gently fold these in. Then add the rest of the whipped egg whites and fold these in until you can no longer see any lumps or streaks of egg whites anymore.

Gently pour this into your tin, on top of the flan mixture. They will mix together a little, this is ok.

We're going to bake this in a water bath. So add this tin into a large baking/roasting tray that has high sides.

Pour boiling water into the large tray until the water reaches about half way up the sides of the tin with the batter in it.

Carefully place this into your oven and bake at 180c/350f for around 55-60 minutes, or until a toothpick inserted into the cake comes out clean. It will be very jiggly at this point, don't be alarmed it's just the flan, this will set as it cools.

Take this out of the oven and leave to cool completely, then place it into your fridge and leave it there overnight.

The next day take it out of the tin, cut into it and enjoy!