Pre-heat the oven to 160'C. Grease and line a 20cm square baking tin. 

Peel and thinly slice (lengthways) 2 of the bananas. Swirl 2 tbsp of caramel in the bottom of the tin so it is thinly coated. Lay the banana slices on top and set aside. 

Mash the 4 remaining bananas and add to a large mixing bowl. Add the sugar, butter, eggs, flour, cinnamon and 1 tbsp caramel to the bowl and mix using an electric whisk or wooden smooth until fully combined. 

Pour the cake mixture over the bananas and caramel in the tin, being careful not to move or dislodge them. Smooth the top out and place in the centre of the oven. Bake for 40-50 minutes until a skewer inserted in the middle comes out clean.

Remove from the oven and cool on a wire rack for 10-15 minutes. Then place a chopping board over the top of the tray and (wearing oven gloves because it will still be hot!) turn it upside down so the cake comes out on the board, banana side up.

Place the remaining caramel in a bowl and microwave for 40 seconds until warm and runny. Cut the cake into squares and serve warm with the caramel sauce drizzled on top.