I was working on my first fondant covered cake for my daughter's birthday--a feat in itself! Since I wanted everything to turn out just perfect I started searching for a good buttercream recipe to go under the fondant. The recipes I found were either for very large amounts, didn't sound very tasty, or were the kind of buttercream that would not hold up well for the purpose I needed. Therefore, I went with a half Crisco/half butter mix. I used 2 tsps of meringue powder (the equivalent of one egg white) to improve the texture. Went on beautifully.
In a large bowl mix Crisco and butter at high speed until smooth and fluffy--about three or four minutes.
Reduce mixer speed to low and add meringue powder and extracts. Increase speed and blend for another minute.
Reduce mixer speed to low again and begin to add powdered sugar, one cup at a time. You will probably need to stop and scrape down the sides with a spatula to ensure all the powdered sugar gets blended.
Once all the powdered sugar has been added, check the consistency. You should be able to easily frost a cake without worrying that you are going to tear the cake or cause it to crumble. If it is too stiff, add the water and blend. I would start with half the water and see how it is before adding the rest of it. The humidity can really make this vary, so don't assume that what worked last time will work exactly the same again. Your end result should be fluffy, smooth and tasty and more than enough to frost a 9 inch round layer cake or a 9 X 13 cake.