I have been making buttercream now for many years and always use the same recipe where there is half the butter to icing sugar regardless of the amount being made.
500g icing sugar (sieved)
250g butter (any kind; I prefer salted to unsalted but both will work fine)
1 tsp vanilla extract
1 tsp boiling water
This amount should make sufficient to ice around about 8-12 cupcakes dependent on the style of icing or one standard size sponge (either iced in the
middle or on top or used to put on a thin coat on the sponge before you coat it with sugar paste.)
Either use a stand mixer or hand held mixer. The buttercream can be made by hand but it is harder to get the same light finish .Beat the butter on its own for about 5 mins until it is light and increased in volume. Gradually add the icing sugar and when this is incorporated add in the vanilla extract. Finally add a teaspoon of boiling water and beat again.
To make a chocolate buttercream add 120g of melted and slightly cooled chocolate I prefer to use dairy milk but again any kind will do .Food flavourings can be used or simply add a spoonful of
jam or lemoncurd or your favourite spread – Nutella, for instance.
Gel or paste food colours are equally as good to colour buttercream and usually only a tiny amount is needed.
Buttercream can be stored in the fridge for a couple of days but it freezes very well and I tend to make extra each time so there is always some to hand in the freezer. It’s just a matter of defrosting it and giving a good beat to make it smooth again. I use water in my recipe rather than milk so the cupcakes/cake will be fine for a couple of days out of the fridge although sponge is best eaten on the day it is made.
When filling your piping bag with the buttercream pop it into a jug and fold the top back over the rim of the jug which gives you a nice open bag to fill. One final little tip- Before putting your piping bag into the jug snip the end off and put in your chosen nozzle. If you think you will need to refill your bag with more buttercream or you want to use different colours using the same nozzle put the nozzle into the snipped piping bag as before but fill a separate bag with the buttercream. When you are ready to pipe snip the end off this second bag and put it inside the piping bag with only the nozzle in. This means you can change bags and colours with the minimum of mess.