• Preheat the oven to 160 °C. Grease the sides of a loaf pan using spray oil.
• Add the butter and sugar to the bowl of an electric mixer and beat for 2-3 minutes, until light and fluffy.
• Add the eggs, one at a time, beating between each addition. Add in the vanilla extract.
• Sift the flour and fold through the butter mixture until everything is just combined.
• Pour the batter into the loaf tin and bake for one hour, until a skewer inserted comes out clean. Leave to cool.

Icing

• Combine the butter and icing sugar in the bowl of an electric mixer. Add the vanilla and milk.
• Stir the mixture until smooth. You may need to add a small amount of additional milk if the mixture is too thick.
• Spread the icing over the cooled cake and then decorate with sprinkles.