Preheat oven to 180*c/350*f/Gas Mark 4/160*c Fan Oven.

Line a cupcake tin with cases and set aside

Place the eggs and light brown soft sugar into a bowl and using an electric mixer beat together until light and fluffy, this normally takes around 1-2 minutes.

Add the oil and vanilla paste, mixing until just combined.

Stir through the mashed banana.

Add the self raising flour and cinnamon and blend until fully combined, being careful not to over mix, and spoon the mixture into your prepared tin.

Cook for 20 to 25 minutes, until light and fluffy. You can tell it's ready when it springs back when lightly pressed. You could also insert a skewer into the middle of the cake and if it comes out clean, then the cake is ready.

Once ready, remove from the oven.

Allow the cakes to sit in the tin for roughly 5 minutes, then place on a wired rack to cool.

Whilst waiting for them to cool, start making your icing.

Add the butter to a mixing bowl and using an electric mixer, blend until creamy.

Add half of the sieved icing sugar to the bowl and using a spoon, gently stir together until just combined (this helps to prevent an icing sugar explosion!), before mixing with the electric mixer.

Add the remaining icing sugar and follow the steps above, do not be afraid to overmix, you want this to be nice and smooth.

Add the vanilla paste and blend, then add in the custard until fully combined and the icing can hold it's own shape

Now the cakes have cooled, start to prepare the middle. using a sharp knife, cut a 'well' out of the centre of the cake, as if you were making a butterfly cake. Discard (or eat!) the dome of cake that you've just cut out as you won't be needing it anymore.

You can either pipe the icing on top of the cake, or place some icing on each cake, placing directly on top of the custard.