Cornish Banana Cake

Ingredients

• 8 ounces very ripe banana (weight after peeling)
• 3 1/2 ounces caster sugar
• 3 1/2 ounces butter, softened
• 200g self raising flour, sifted
• 1 egg, beaten
• 1/2 teaspoon bicarbonate of soda
• 1 tablespoon milk
• 1 ripe banana
• 2 ounces butter, softened
• 2 ounces caster sugar
• 1 soft, very ripe banana
• 1 ounce cocoa powder, sifted
• 8 ounces icing sugar, sifted