White chocolate ganache - please help!

[FringeEvent]

I recently made a chocolate and coffee marble cake with a white chocolate ganache topping - first time making a ganache, no idea what I was doing - I followed the recipe to the letter but it was far too liquid when I spread it over the cake, and it ran straight off :(

The recipe I used is below.

Could someone with a bit more knowledge than I have please help me adjust this, or just give me alternative ingredients/instructions, so I end up with a lovely thick spreadable ganache? I want to make this cake again to take into work on Friday, we're hosting a fund-raising coffee morning for Macmillan's World's Biggest Coffee Morning :)

? 100g good-quality white chocolate, finely chopped
? 80ml whipping cream
? 20g unsalted butter
Method: Heat cream and butter until hot but not boiling, pour it over the chocolate. Leave to stand for a couple of minutes, then stir gently until smooth and glossy. Leave to cool and thicken slightly, then stir gently. Spread over the cake.

I wonder if it just needed to be left to thicken for longer than the recipe states? It's pretty vague about how long it should take, I think I put it in the fridge for a couple of hours (the recipe doesn't actually mention refrigerating it - could this be where I went wrong?? Maybe I should have left it out on the side)

Yes, you leave it until its spreadable or pop in fridge. It should be spreadable. You can also add icing sugar is you wanted a harder finish.

Saying that white chooclate isnt the same as dark chocolate and if white the recipe should be contain a higher amount of chocolate.

So do the proportions of chocolate to other ingredients seem wrong in the recipe? (I haven't made a regular chocolate ganache either!) I can't see how that much cream and melted butter would end up being anything other than liquid. I wonder if it's worth getting some spare white chocolate in case it just doesn't reach spreadable consistency, and I could then just melt the extra choc gently and stir it in.

Great tip on the icing sugar, I'll bear that in mind.

I've just realised I'm a week ahead of myself, I thought the event was this Friday but it's not til next week, so at least I've got time to get this right! Might do a practice run and use it on some cupcakes.

Fringe i dont use whipping cream, its always double cream, big pot of cream, think its a 285ml pot, and always 200grms bournville or similar, when it gets cold its thick enough to pipe, ( i used it to pipe into profiteroles) nice!

I use 150g of plain choc to 65g butter. I let it cool a little and then whisk it with a balloon whisk until it goes the colour of milk choc or a little darker and then use it like a frosting.

You can just let it cool a little and then pour it over the cake.

I think the key is letting it cool enough so that it's still pourable but has thickened a little.