The question “Can you ganache a fruit cake?” is a bit of a loaded one. There’s really three answers to that. There’s the old-school, traditional fruit cake decorator answer of: “Of course not! Blasphemy! Fruit cakes are covered in marzipan, then fondant. The end.”
Then there is the semi-traditional answer of: “Of course not, fruit cakes are covered in almond icing (almond flavoured fondant) and then fondant. The end.”
Then there is my answer/personal opinion: “Sure, if you want. It’s not traditional, but it’s your cake. As long as you don’t need to keep it for months once it’s covered, then if you wanna ganache it, ganache it. Ain’t no one going to hunt you down and smother you with a block of marzipan for daring to cover a fruit cake in chocolate. The end.”
My answer is a little wordy and maybe not that eloquent, but if you’re here reading this, then it’s probably the answer you were hoping for, right?
The main reason (that isn’t taste related) that you can’t cover a fruit cake in ganache is if you need to keep it for a long time after the fondant is applied. Ganache will keep safely for a week or two under fondant (maybe a bit longer depending on the room temperature) but compared to a marzipan-and-fondant covered cake which can keep for months, the ganache has a much shorter keeping time. If you need to keep it longer, you’ll need to stick with (pun intended) marzipan or almond icing. But, if you’re covering your fruit cake on a shorter cake decorating timeline, then you can ganache the cake just as you would any other flavoured cake.
I know fruit cakes aren’t terribly popular these days, but often (especially for wedding cakes), people like to have a tier or two of fruit cake amongst other flavours, either as the top tier to be stored for the first anniversary, or for the fruit cake lovers in the family (let’s not pretend, it’s usually the older folk).
The problem starts when you want to match the fruit cakes to the other tiers. Like most cakes, fruit cakes tend to shrink away from the tin a bit, but usually mainly along the top edge, which leaves you with a slightly tapered cake. Unless you try and roll out the marzipan/almond icing/first layer of fondant, thicker along that top edge to try and even things out, just placing a regular layer of icing won’t fix that taper, and if your other tiers are beautifully ganached/buttercreamed with perfect straight sides then the fruit cake tiers will stick out like a sore thumb.
Here’s the thing, I have a trick that will (hopefully) keep everyone happy, the old-school almond lovers and ganache lovers alike. It’s this good stuff in this teeny weeny bottle right here…
If you add this Lorann Amaretto oil to your white chocolate ganache, you’ll end up with a ganache that tastes almost exactly like almond icing, and somewhat similar to marzipan. Other oil or alcohol based almond extracts would also give a similar effect (just don’t use anything water-based or you risk splitting your ganache.) I got this Lorann oil from Kiwicakes, but it seems to be pretty readily available in most countries, and of course all over the internet.
All you need to do for your almond ganache is make your regular ol’ white chocolate ganache (check out my ganache tutorial if you’re not familiar with making and using ganache) and add the oil/extract to taste. You will need to taste it (sorry if you don’t like almond) as the strength of the extract and the amount of ganache you’re making will affect the amount of flavouring you need. You’re aiming for a light almond flavour that just takes the edge off the white-chocolate flavour.
I’m only semi-ashamed to admit that years ago I made a cake for some older, traditional fruit-cake loving folk, and they didn’t actually realise that the icing under the fondant was this ganache and not almond icing. I know there are some people out there who like dark chocolate ganache on fruit cake. It’s not my cup of tea (and I’m as fussy about tea as I am about, well, most things) but if you fancy it, then why not?
Since you’re only covering the outside of the cake with the ganache (I wouldn’t suggest attempting to slice a fruit cake into layers… hello mess, hello fruit falling out everywhere, hello frustration – I’m with the traditionalists on this one!) you will need to try to bake your fruit cake to a similar height as the rest of your cake tiers. If, like me, you like tiers that are 4″+ tall, you’ll need to adjust your recipe to make sure you have enough batter to give you that height. And of course I suggest using baking strips on the tin to slow the baking of the outside of the cake so you don’t end up with burnt fruit. Because here’s how I feel about burnt fruit.
I think that’s all I really need to say about that.
Long story short: yes, you can ganache a fruit cake if you really want to.