I remembered the recipe I learned in decorating class. 2/3 cp Crisco, 1/2 cp water, 1 tsp vanilla & 2 lbs powered sugar. If you want it pure white use clear vanilla other wise it will be off white & you can add butter flavoring too. If you use real butter or margarine it gets too soft from the heat of your hands when you decorate. This will be a little stiff but is good for flowers & stuff. To spread on cake add more water to make easier to spread. Have used this for almost 27 years & everyone always loves it. If you are not going to pipe it on a cake you can use half butter & half Crisco to get a richer taste just beat till real fluffy. I found a Martha Stewart recipe for true butter-cream but it is complicated & I made a mess of it. It was a lot of work & didn't turn out that good. I failed Martha 101.