1. Preheat oven to 180°C/350°F/Gas 4. Lightly grease and base line a 20cms/8" round tin.
2. Beat the butter and sugar together. Add the yogurt, bananas, egg and vanilla essence. Beat until smooth.
3. Sieve in the flour and bread soda into the mixture and mix well. Gently stir in the melted chocolate until it looks marbled۪.
4. Transfer to the prepared tin. Bake for about 40 to 45 minutes until risen and firm to the touch. Cool in tin for 5 minutes then transfer to wire tray to cool completely.
5. Warm the chocolate and cream until chocolate has melted. Stir well, and then allow to cool and thicken.
6. Spread over cold cake. Cut into squares or slices.

To Decorate: Add some banana to the top of the cake