Preheat the oven to 180°C/fan 160°C/gas mark 4 and grease a 20cm cake tin. Drain the jackfruit and rinse well with cold water.
In a medium saucepan, cook the granulated sugar over medium-high heat, swirling as needed, until an amber caramel has formed, 2-3 minutes
Take off the heat and add the softened butter and stir constantly until fully melted in.
Immediately pour into the cake tin, spreading to cover the entire bottom of the pan. Arrange the jackfruit in an even layer over the caramel.
Place the butter and brown sugar into a bowl and beat with an electric whisk on a high speed until pale and fluffy. Beat in the eggs one by one and then add the vanilla. Sift in the plain flour, baking powder, salt and ginger and stir to combine.
Spoon into tin over jackfruit and smooth out the top.
Place in oven on middle shelf for 40-45 minutes until cooked or until a skewer is inserted into the middle of the cake and it comes out clean.
Once cooked, leave to stand on a cooling rack and once cool enough to handle, turn out onto a plate and serve.