Milk Chocolate and Banana Cake

Sponge

• 200 g bananas, very ripe, cut in pieces
• 3 large eggs, 2 separated, 1 whole
• 90 g sunflower oil, plus extra for greasing
• 50 g whole milk
• 150 g caster sugar
• 150 g self-raising flour
• 100 g milk chocolate chips
• ½ tsp bicarbonate of soda
• 4 Tbsp cocoa powder

Chocolate Icing

• 100 g milk chocolate, small pieces or callets
• 100 g sour cream