I, like many others, have used white margarine in my buttercream for the longest time. I was able to purchase it from my friends who owned their own cake supply shop. In the past couple years, they closed their shop. I know they had said white margarine is something they couldn't get either. Their supplier was another cake shop in Pennsylvania. Last week I was desperate. I thought I had some of the precious stuff stashed in my spare refrigerator downstairs, but, alas, it...