Hello, 

I am trying to make ganache. I used about 210 g white chocolate and 75 g heavy cream. I boiled the cream and poured it over Giradelli white chocolate chips. However, the chips are not melting, they are just clumping. So, I put them on top of a boiler and then some of them melted but its a very clumpy mixture. 

Any ideas on what I can do to fix it?

Also, if I whip up this mixture (hoping everything melts properly), how long can I leave the cake with whipped ganache out since it will have gumpaste decor on it. 

I appreciate any help since my cake is being delivered tomorrow!

Are they chips meant for going into for example chocolate chip cookies or is it chips of melting chocolate?

I don't make white chocolate ganache, but regular chocolate chips are a bit different in their behavior than melting chocolate is...

Hmm. Well, they do have a giant chocolate chip cookie picture on the packaging. But, I always use giradellehi chips for my semi sweet chocolate and never ran into trouble.

Was the cream actually boiling?........it may have been too hot

Nope, as it started to bubble on the sides, I took it off. BUT. I do think it may have been too hot for white chocolate, since WC just tends to be ridiculous with heating. :/

Did you start to mix it as soon as you put the cream on the chocolate? I find that I need to leave the cream/chocolate for a minute or else the chocolate seizes.

I imagine that the minute just sitting there allows the chocolate to accept the temperature difference but I am not basing that on anything other than my own judgement.

Also I use white chocolate a lot in ganache and I personally find that as long as it is left to sit once the cream is added then it works just as easily as milk chocolate.

can you strain it

Ah, I think I may have mixed it a bit early. 

I did end up straining it and using it as a filling instead of frosting! 

Before, I had exactly the same problem as you. Now I melt the chocolate first over a hot water bath and then I put the cream. Works just fine.

I wonder if moisture got into the chocolate and that is why it seized. Maybe it was due to storage (was it a brand new pack that you opened? How was it stored?) I don't let chocolate rest but stir it immediately to aid melting. I do not use chocolate 'chips' which are meant to be bake safe (so they do not melt in the oven). Why not microwave the chocolate next time and see how it behaves? Please come back and let us know if you manage to make the ganache with this product and what method you used.

Chocolate chips are compound chocolate not couverture.  The compound chocolate is vegetable oil based, with very little if any cocoa butter.  

Compound chocolate melts at a higher temperature than couverture because of the cocoa butter replacer.  It also thickens into a useless blob when the temperature is too high.  If you have a clumpy blob, it's been exposed to temperature above 115 degrees. I stopped using  compound chocolate, but in the past I found the best way to melt it is in a double boiler.  Make sure the pan does not come in contact with the water and set the pan over simmering water, not boiling.