Preheat the oven to 180°C/160°C fan and lightly grease and line an 8 inch round cake tin.
Set aside 50g of the caster sugar for later.
Whisk together the remaining caster sugar and eggs for 2-3 mins until paler in colour.
Mix in the milk, oil, vanilla extract and mashed bananas.
Sieve in the flour and bicarbonate of soda and fold until fully incorporated.
Gently fold in the raspberries.
Fill the prepared cake tin with the cake mixture and level it with a spatula/back of a spoon.
Sprinkle the set aside caster sugar over the top of the mixture.
Bake in the oven for approx. 45 minutes. A cake tester/toothpick should come out clean when inserted into the centre of the cake. A few crumbs are fine.
Leave to cool in the tin for 15 minutes, then remove from the tin and leave to fully cool on a wire rack. You want the cake to cool the right way up to get a cracked effect on top.
