Step 1

Preheat oven to 160°C and grease a 24cm bundt pan.

Step 2

In a stand mixer fitted with the paddle attachment, beat butter, cream cheese and sugar together until thick and pale. With the motor running, add eggs, 1 at a time, beating well after each addition. Add banana and beat until combined. Sift cocoa and flour together. Turn off mixer and fold through cocoa mixture and buttermilk.

Step 3

Pour into prepared pan and bake for 1 hour 30 minutes or until a skewer inserted into cake comes out clean. Cool for 15 minutes in pan, then turn out onto a wire rack.

Step 4

Make butterscotch when ready to serve. Place butter and sugar in a saucepan over medium-low heat, stirring until sugar is dissolved. Add cream and bring to a simmer. Simmer for 5 minutes or until slightly thickened, then stir in chocolate and simmer, stirring, for 2 minutes or until melted and smooth. Pour butterscotch over cake just before serving.