Can I re-soften chocolate ganache?

[mejon]

I have made some (rather lovely even if I do say it myself!) chocolate ganache to spread in and on DD2's birthday cake tomorrow. The recipe I used said it could be refridgerated for several weeks and can be whisked to make it spreadable. It's been in the fridge for a few hours and is set hard - I can't see whisking being possible so how can I re-soften it to make it spreadable? Can I give it a quick whizz in the microwave on a low setting or will leaving it out at room temperature for a few hours work? It'd be a shame to have to eat it all myself with a spoon .

I've warmed it up over a bowl of warm water before, so can't see why you couldn't microwave.

Spoon idea is better tho

Thanks. I'll try the warming over hot water first and see how that goes.