1. Preheat oven to 180C or 160 fan.
2. Start by creaming together your butter and sugar until light and fluffy. I like to use my Kenwood kMix for this, but you can also use a wooden spoon and a bowl.
3. One at a time crack a egg into your mixture mixing really well before adding in the next egg. Your mixture may become slightly curdled from the eggs, but don’t worry as it will come together once the flour is added. You can also add your vanilla in at this stage.
4. Sieve in your flour and baking powder and carefully fold this through, it’s so important you carefully do this as we don’t want to knock out any of the air. Once the majority of the flour is folded into the mixture and there is just a little bit of flour left, add in your milk and continue to fold until you have a smooth cake mixture.
5. Pour your mixture into a greased and lined rectangular baking tin or tray, and bake in your preheated oven for around 25 minutes but thus can depend on the size of your tray. The cake will be done once it’s well risen and a cocktail stick comes out clean.
6. Once baked allow the sponge to cool and get ready to decorate. Make the icing by gradually adding water to your icing sugar until you get a thick but runny icing. Then spread your icing onto the top of the cake and finish of with your sprinkles. Enjoy!