Depending on the temperature of your house, you are definitely going to need that extra tablespoon of cream. I did not allow myself enough time for decorating, so I had to skip the crumb coat, but luckily, the cake did not shed much and the frosting was so silky and spreadable that it did not pull up the crumbs. I am totally stealing the idea for the flowers up the sides of the cake on the web page. That looks precious, and you can do the whole thing on the cake without having to transfer flowers, you only have to change piping tips for the green, and you can do the sides while seated, which works great because you're working at eye level. Vanilla extract works better than vanilla paste in this recipe, but if you have to use the paste for whatever reason (ran out of extract, avoidance of any alcohol-containing products, whatever), the color is going to be a very light beige instead of white. Even yellow gel food coloring will cover it, but if you want a white cake, maybe use powdered vanilla extract instead. I do not recommend commercial icing whiteners, as they contain metal oxides.
