This easy but delicious cake features two layers of wonderfully moist, banana-flavoured sponge studded with chunks of dark or milk chocolate. The layers are sandwiched together with a simple vanilla-flavoured buttercream.
Use really ripe bananas for the best taste. A little cinnamon enhances the flavour without dominating, but leave out if preferred.
Preheat the oven to 180°C / 160°C Fan / Gas 4 / 350°F.
You will need two deep, 18 cm round, non-stick cake or sandwich tins, ideally springform or loose-bottomed. Line the bases with baking paper and grease the bases and sides with butter.
Stir together the flour, baking powder, cinnamon if using, and the salt.
Sift into another bowl then set aside.
In a large bowl and preferably using electric beaters, beat together the butter, sugar, and vanilla extract. Scrape down the sides of the bowl as necessary during this and subsequent steps.
Beat in the eggs one at a time along with 1 rounded tablespoon of the sifted flour mixture each time.
Beat in half the mashed banana with another rounded tablespoon of the flour, then the remaining mashed banana and another tablespoon of flour.
Gently but thoroughly fold in the chopped chocolate and the rest of the flour.
Divide the mixture between the two prepared tins, ideally weighing for accuracy, and smooth the tops.
Put in the oven and bake until risen, set and golden brown: when done the edges should be pulling away from the sides of the tin and the tops springy when lightly pressed (approximately 20 - 25 min).
When done, transfer the tins to a wire rack and leave to cool for 10 minutes.
Carefully remove the cakes from the tins and put on the rack until completely cold.
While the cakes are cooling: make the vanilla buttercream
Beat the butter until very soft.
Gradually beat in half the sifted icing sugar, followed by the vanilla extract, then the rest of the icing sugar and the milk.
Set aside until the cakes are completely cold.
Assemble the cake
Turn one of the cakes over so the underside is now uppermost and spread it with the vanilla buttercream, making sure it goes right to the edges.
Place the second cake on top, right side up, and very gently press down to secure it.
Dust the top of the cake with a little sifted icing sugar.
Stored in an airtight container the cake should keep at least 3 - 4 days.