Last night I tried to cover a 12" square cake, that was iced with dark chocolate ganache.

I rolled out the icing and draped it over the cake, but I hadn't moved it over enough so have the side was not covered, I tried to very gently take it off but I tore it and I had spent too long rolling it out, it was also a bit dry so I just had no luck at all.

If were white buttercream, I could have just kneeded it again and rolled it out.
But because it was all dark chocolate ganache under one side, I had to throw it out and start again.

There was probably 1.5 - 2kg of wasted fondant. Something I didn't quite take into account at the time of quoting.

So not only will I profit less, I had to end my evening early and need to go shopping today for extra icing! There goes my valuable Friday night

Very sorry that happened to you. Thank you for sharing your experience though. It could save someone here precious time and money.

I have had this happen more than a few times .... you can actually fix it.

Lay your choc streaked fondant out and wipe down with damp Viva paper towel or a new damp chux/or cloth. It will make your fondant a tad wetter just re knead and and let it sit for a little before re trying. If you really can't get it all off just knead it and set aside for when you require coloured fondant for another order.

Do you leave your ganached cake to 'set up' before covering in fondant? I do this and the ganache surface is firm and dry by the time I cover with fondant, so that if I have to lift the fondant and re-roll it picks up next to no ganache at all.

I always leave my ganache till it is dry and set as well, I usually ganache one day and ice the next, I just brush with a little sugar syrup to stick the icing on.

I brush the ganached cake with crisco before covering, it helps adhere the fondant but also stops any coming off if you need to recover. If any does come off with it, it makes it easier to rub off too.