As a baker based in the UK I had never even heard the term "Frosting" until I discovered American recipes online. I wasn't sure if this was some new special 'thing' or if it was equivalent to something we have here.
If there is a difference in the nature of the icing we use in the UK (and Europe) we highlight that with its own specific name, Royal Icing, Buttercream Icing, Glace Icing, Fondant Icing and so on. But they are all something you Ice a cake with so I investigated this mystery term 'Frosting' a little further.
I have come to believe that Frosting is an Americanisation of what I would call Buttercream or some variation thereof. In as much as it has a buttercream base, but isn't what we in Europe would call traditional buttercream.
I googled frosting recipes and found that they were by and large Buttercream recipes, meaning they all had butter and icing (powdered/confectioners sugar) in the ingredients, but not just those 2 defining ingredients. Sometimes there were variations, some with marshmallow fluff and others with cream but they all had a Buttercream base.
Interestingly, in America, they have a different definition of Icing, they don't use it as a blanket term for all possible cake coverings which involve sugar in the making. When you say 'Icing' in the States they very specifically think of Glace Icing, which is simply icing sugar and a fluid like water or milk, maybe a fruit juice of some kind. The kind of thing you might pour onto little fairy cakes for a kids birthday party.
This may not be a revelation to most, but it is an important distinction because they serve different purposes and you can buy different types of icing sugar to make them. I, for example, have made my own marshmallow fondant before and found, unsurprisingly, that if I used Fondant Icing Sugar the result was smoother than regular icing sugar, though I could discern no difference between the powdered sugar's themselves. You also need less of the Fondant Sugar for the process.
So how do we make our distinction? I once had a very fulfilling discussion with a friend over what constituted a Butty rather than a Sarnie (Sandwich). We realised we had 2 different words for something that was basically edible stuff between 2 bits of bread. We concluded that heat was the critical component and while the term Sandwich was universal the term Butty was not. For example, you could have a chip butty or a chip sarnie (assuming here the chips are hot) but you could not have a salad butty, that only works as a sarnie. So in order for something to qualify as a butty the filling must be hot and melt the butter. And if you don't have butter on your bread at all the rule still applies, you are just a freak ;)
I'm sure you are asking, what on earth are you on about? But it does speak to my headline question.
Why is something Frosting rather than Buttercream? Well, generally speaking, they are similar. However, I think the answer is one special ingredient. Frosting, or American Buttercream, uses Shortening. Usually with butter, but also in total replacement of butter. This makes the icing whiter and can make it more stable. However, shortening is refined fat, which is why it is more stable, it melts at a higher temperature than butter. Specifically, refined vegetable fat. In the UK we call it Trex. It basically vegetarian-lard.
Here is a well reasoned and very thorough recipe for Frosting but I can't say I am tempted to give it a go. Maybe that is just a cultural aversion, given what we usually use Trex for in the UK. But I have also heard lots of British bakers say they don't like the mouth-feel and there is a greasy residue, which I would expect.
In my next post, I'll break down the basic recipes & methods for the major icing types. Do you have a favourite type of icing to work with?
Have you tried buttercream with shortening? I'd love to know!