Apologies to all my international readers, but this little handy tip might only be of use to you if you are in the UK.
It happened out of necessity. I had a cake to ice but had no butter or anything else to make butter icing, all I had was a packet of Angel Delight butterscotch flavour. I mixed it with half the quantity of milk advised and then added icing sugar until it was cake frosting consistency. If you add even more icing sugar to make a stiffer paste you could use a piping bag, so I may do this next time. If you use skimmed milk, then this is a much much lower fat option than regular butter icing, and I have to tell you...it was DELICIOUS !
Really finger lickingly delicious! I had enough to top and fill a regular sponge cake and some left over for a batch of cupcakes. It kept fine in the fridge for a week.
Now I can't wait to try this with the other flavours available!!!