1. Preheat the oven to 170°C.
2. To make the banana purée, caramelise the sugar then add the banana and cook out until a purée is formed. Mix until smooth.
3. For the banana cream, whisk the cream until soft peaks forms. Add the purée and alcohol and whip until thick.
4. For the ginger cake, place the butter, sugar, and syrup into a bowl and melt over a bain marie, add the purée and mix well. Add the egg and mix well. Add the flour and mix until just combined.
5. Pour into a greased, lined tin and bake for 12 16 minutes until a skewer comes out clean. Allow to cool fully before cutting.
6. For the sauce, place the sugar, saturated with water, into a pan over a high heat. Allow to boil and caramelise.
7. Bring the cream to the boil, add to the caramel with the butter and whisk until combined. Finish with the salt.