swiss buttercream

Hello, I am so pleased to find this group. I've learnt so much from reading all the forums! I am attempting to make my first novelty cake for my daughter's 'Disney' themed party. I don't want to be too ambitious but I am adamant that it will be a home-made cake. I am thinking something like...

Advice please. I'm making a cake for a wedding celebration for my daughter and it's going to be 4 layers of 8" vanilla sponge. In fact, cakes are made and in the freezer. When it comes to the icing, I'm completely conflicted about what kind of butter cream icing to use. I've read so many blogs...