Preheat the oven to 190C/375F/Gas 5. Place the butter, sugar, cream and maple syrup in a small pan and heat gently, stirring from time to time until smooth.
Meanwhile, roughly crumble the cake into a small ovenproof dish. Slice the banana and mix with the cake.
Pour over the sauce and bake for 10 minutes until bubbling. Serve warm with cream or custard.
