Preheat the oven to 180C/350F and line an 8x8 inch square baking dish. You can also spray with cooking spray and place a strip of grease proof paper across the pan. Make sure you have enough overhang, so you can lift the cake out later.
Place you bananas into a large bowl and mash with a fork. Add in the slightly cooled melted butter, egg, vanilla, light brown sugar and caster sugar. Whisk until well combined and smooth.
Next, add the baking powder, bicarbonate of soda, cinnamon, salt and flour. Mix until well combined and there are no lumps of flour.
Tip the batter into your prepared pan and spread into an even layer. Place in the oven for 22-25 minutes.
While the cake is baking, place the caramel, salt and 2tbsp of single cream into a small, deep saucepan on the lowest heat. Stir continually until the caramel has softened and the cream is combined. Don't bring it to a boil, just gently warm. This will take a good 10-12 minutes. Leave to one side while the cake finishes baking.
Cake is ready when risen, golden and an inserted skewer in the centre comes out clean. Remove the cake from the oven and spoon the still warm caramel sauce onto the the cake Gently spread until the cake is covered.
Leave to cool for at least 30 minutes. You can dig right in then, or wait a little longer for it to cool completely. I waited for 60 minutes before gently lifting the cake out and placing on a cutting board. It will still be slightly warm. Slice into 12 squares and place a fresh slice of banana in the centre of each cake slice. Serve with ice cream, if desired. You can serve this cake warm from the oven, at room temperature or reheated in the microwave.
Salted Caramel Banana Cake will keep in an airtight container, in the fridge, for 4 days. Banana flavour will intensify after a couple of days. Bring to room temperature before serving.