Preheat the oven to gas mark 4 / 180*C / 350F
Line an 8 inch/22cm round loose based cake tin with Bakewell non stick siliconised baking paper.
In a large bowl add 175g of butter, 175g caster sugar, 175g of self raising flour, 3 large eggs, 1 teaspoon baking powder and 2 teaspoons vanilla extract. Mix with an electric whisk until thoroughly mixed together.
Stir in 100g of blueberries to the mixture. Carefully spoon the mixture into the tin and level off with a spatula.
Bake for 50 minutes or until it feels firm to touch.
Cool for 10 minutes and remove the cake from the tin. Transfer the cake to a wire rack to cool fully.
To make the vanilla icing: Whisk together 500g of icing sugar and 150g of unsalted butter until thoroughly mixed together.
In a separate bowl mix together 50mls of whole milk and 1 tablespoon of vanilla extract. One bit at a time add this to the sugar and butter mixture. Stirring thoroughly.
Spread the vanilla frosting on the outside of the cake. and garnish with blueberries.