This is one yummy buttercream! Reminds me very much of the buttercream that was on my wedding cake!
Taste as you go, but I do recommend adding a little extra rum.
I cut the batch in half for my two apple cakes and had to use the same amount of rum that the recipes for twice as much called for. (this of course could be due to the brand of rum as well)
Lovely recipe! Perfect with an Autumn apple cake!