Pre-heat the oven to 180/160 fan Celsius and line an 8 inch baking tray with parchment paper.
Mix the butter and sugar in a bowl with an electric hand whisk (you can use a normal whisk or wooden spoon if you don’t have one) – mix them together until the mixture is pale.
Add in the eggs and vanilla extract and whisk until light and fluffy, then sift in the flour and baking powder and mix until combined.
Pour the mixture into the lined baking tray and place into the oven for 25-30 mins.
Once baked, allow the cake to cool before adding the toppings
Toppings
Mix together the icing sugar and water until it becomes a paste. Add more water if you want it to be thinner consistency.
Spread onto the cooled sponge cake, scatter on the sprinkles and enjoy!