Here is my definitive list, ranking the most common types of cake buttercream, from best to worst.
Buttercream is, quite literally, the icing on the cake. It has the power to elevate the humble cake sponge to God tier. Some people actually consider cake as a vessel for transporting frosting into their mouths, and I don't judge them. Cake sponge alone, by itself, is basic. With a beautiful buttercream it has the opportunity to look so much better and offer a whole different tasting experience.
Buttercream can be used in various different ways - piping, filling, layering, coating. It also helps keep cake fresher for longer by adding a barrier to air in the atmosphere which could dry out the sponge. However, not all buttercream are made equal and you will know why here.
5 Best Types of Buttercream for Cakes
1. Swiss Meringue Buttercream
This is the Queen of Frosting. Imagine the melt-in-mouth texture of ice cream, just at room temperature. Making Swiss meringue buttercream ("SMBC") is more laborious than others as it involves cooking egg whites and sugar over a double boiler before whipping up to a meringue and then incorporating butter into it. But the effort is worth it.
It uses less sugar than ordinary American frosting so the sweetness is well balanced. The texture is smooth and lush, without being heavy, greasy or gritty. It stays silky smooth at room temperature and doesn't crust.
It is also incredibly stable and versatile. It holds up well in tiered cakes, used as fillings in between cake sponge layers, and also for piping onto cupcakes or flowers and other decorations. This entire cakescape is decorated using SMBC to fill and stack the tiered cakes, piped swirls and the seagrass.
It can be used to fill eclairs and macarons. It can also be coloured and flavoured in numerous ways at the end either by adding food colourings, cocoa powder or melted chocolate, nut butters, fruit purees or even alcoholic liqueurs.
2. Ganache Frosting
Nothing works as hard as chocolate ganache to make a cake into a showstopper. Warm it up to drip it over cakes or glaze patisseries with. Roll it into truffles. Fill it in pie crusts to make tarts. Whip it till it's turned into an airy frosting to fill and cover cakes with. Cool it down to pipe into flowers or fill macarons.
Dark chocolate ganache is my favourite ganache to work with - any bitterness is tempered down with cream or butter and it complements the sweetness of the cake sponges so well. White chocolate ganache works really well for frosting or dripping cakes with. However, I do feel it's a tad too sweet so much prefer it flavoured with other ingredients such as lemon juice, tea, coffee or fruit purees.
Ganache is so hard-wearing that you can even make it without any cream or butter. You can make it with WATER as we do for fake bakes. In this M&S Fake Bake we've used water ganache in three forms - whipped buttercream, drip, and piping.
Due to its limitations on usage with food colourings and thereby scope of decorating, I have to knock it a point.
3. Italian Meringue Buttercream
Italian meringue buttercream is very similar to SMBC in the sense that it uses a meringue base for whipping in butter. However, it can be a bit more daunting as it requires boiling water and sugar into a syrup until it reaches a soft ball stage at around 115 degrees Celsius. That syrup is then drizzled into whipped raw egg whites to make an Italian meringue before adding in the butter.
It is the most stable of all buttercreams and is perfect for warmer climates. It is also the least sweet but is just as versatile as SMBC in terms of colouring and flavouring. The only reason we don't use it is because the egg whites are not cooked through in the beginning like SMBC which would make some of our customers wary. Even though the whipped egg whites are cooked with the hot sugar syrup in IMBC, it is still not the 100% guarantee we would like in terms of being safe to eat for pregnant woman. And for that, I'm going to have to mark it down.
4. Ermine Buttercream
Also known as flour frosting, this type of buttercream is similar to German Buttercream which is based on whipping custard and butter together. To make Ermine frosting, you make a roux from cooking flour, milk, sugar and salt together in a saucepan until it becomes a gloopy thick paste. Once cooled, you then add it into whipped butter and include any flavouring such as vanilla, chocolate, or even cereal milk as I have done so in this rainbow roll cake.
It is close in texture to Swiss meringue buttercream, and shares similar characteristics when it comes to versatility and stability. However, as it is a few more ingredients than a basic SMBC and cooling the roux takes time, I will dock a few points.
5. American Frosting
If American frosting was the only frosting I was allowed to have on cake, I would give up cake entirely. It is ghastly. Made with icing sugar, and butter, or even worse margarine, it is sweet to the point of making my teeth shake. The corn starch in the icing sugar makes it crust and give it a gritty texture too. Yet, this horrific frosting is the most common type made in households, due to its ease, and high street bakeries and supermarkets, due to its low cost.
A lot of American frosting recipes call for 2:1 ratios. That's twice as much sugar to butter. Even the thought of it is triggering a migraine, let alone consuming it on top of more sugar in the cake. Whilst it can take on colour quite well, it's a very stiff frosting to work with and any flavour you add doesn't stand a chance against the sweetness. It doesn't even deserve a photo in this list. Hard pass every time, and I'm sorry if it's hurting your feelings.
I'm not sure if it's obvious from the list ranking buttercream from best to worst already, but we only ever use the best - Swiss Meringue Buttercream. Our recipe has our customers hooked on our cakes, returning year after year for their birthdays (and for some, eventually their weddings and children's birthdays and buttercream birthday cakes!). You can try it for yourself, like countless followers on Instagram have, and be converted for life. Thank me later in the comments!