The crumble topping that is used here adds a welcome crunch and nuttiness, contrasting wonderfully with the softer crumb of the cake. It is a good idea to use ripe bananas in this cake as their developed sugars will taste better and their softer texture will be easier to mash.
240g plain flour
2 tsp baking powder
100 g caster sugar
1 tsp salt
120 ml vegetable oil
150 ml buttermilk
2 eggs, lightly beaten
250 g mashed banana (usually 2 bananas)
1 tsp vanilla extract
50 g brown sugar
3/4 tsp baking powder
75 g plain flour
1 tsp ground cinnamon
1/2 tsp salt
60 g unsalted butter
75 g walnuts, roughly chopped
20 ml pure cream
50 g icing sugar mixture
1/4 tsp vanilla extract
1.Pre heat the oven to 180C and grease and line a 20cm cake tin.
2. First make the crumble by mixing the sugar, baking powder, flour, cinnamon and salt in a small bowl. Then rub the butter in with your fingers until you have a coarse, shaggy mixture. Finally stir through the walnuts. Set this aside in the fridge.
3. To make the cake whisk the flour, sugar, salt and baking powder together in a large bowl.
4. Add the oil, buttermilk and eggs and stir to combine. Finally add the mashed banana and vanilla before giving everything a final stir until everything is just combined.
5. Pour the mixture into the prepared cake tin and then sprinkle over the crumble topping.
6. Bake in the oven for 60 minutes, or until a skewer inserted into the cake comes out clean.
7. Allow the cake to cool for 10 minutes before removing it from the tin. In order to not loose all of the crumble mixture the best way to do this is to place a dinner plate over the top of the cake, then flip the cake over. Remove the cake tin and peel off the baking paper that has stuck to the underside of the cake. Place a wire rack on the bottom of the cake (which is currently the ‘top’ of the cake) and re-invert it over so that the crumble topping is once again facing the ceiling.
8. Once the cake is completely cool gently stir together the icing ingredients (don’t over mix this otherwise you will end up with whipped cream) and drizzle it over the cooled cake.