Preheat the oven to 200C/180C Fan/Gas 6 and line two baking trays with baking paper.
To make the banana cake, pierce the banana skins, place them onto one of the prepared trays and bake for 10 minutes. Once cool enough to handle, remove the bananas from their skins and mash them together in a bowl.
Turn the oven down to 170C/150C Fan/Gas 3½ and line a large, deep 25x30cm/10x12in baking tin with baking paper.
Cream the butter and sugar in a bowl, until fluffy. Add the eggs and mashed banana and mix well.
Pour the milk into a small saucepan and heat until hot, but not boiling, over a medium heat. Add the bicarbonate of soda and stir to dissolve then pour into the cake bowl and mix well.
Fold in the flour, mix through and pour into the prepared baking tray. Bake for 20-25 minutes or until a skewer comes out clean.
Meanwhile, to make the banana miso caramel, place the caster sugar in a saucepan over a medium heat until it starts to caramelise, shaking the pan occasionally to stop it from burning. Add the bananas and muscovado sugar and shake to combine. Cook until the liquid has come out of the bananas.
Add the rum to the pan and cook until the liquid has evaporated. Add the miso, milk and cream and whisk well to combine. Add the butter a cube at a time, mixing each one in until you have a smooth caramel.
To make the sunflower seed praline, place the sugar in a saucepan over a medium heat and caramelise, shaking the pan occasionally to prevent it from burning. Add the sunflower seeds and mix in well then pour into a prepared baking tray and leave to cool. Once cool, blend in a food processor with a few drops of water to form a paste.
To make the miso and muscovado cream, place the miso, muscovado and milk in a saucepan and cook over a medium heat until the sugar has dissolved. Pour into a large bowl and set aside to cool.
Whisk the double cream and crème fraiche together in a bowl until stiff, then fold into the miso and muscovado milk.
To serve,spoon some of the paste onto a serving plate and cut a slice of the cake and place on top of the paste. Top with the caramel sauce and a spoonful of cream next to the cake.