I really need some advice, please!

I like to use ganache under my fondant so that I can get smooth sides and sharp edges where possible.

When I'm asked for 'no chocolate' I use IMBC because it sets up nice and hard in the fridge and I can still attempt a smooth finish. The problem with this is that if I put the fondant on too soon after it comes out of the fridge the fondant gets condensation on it and I can't smooth it. If I leave it to come to room temperature the IMBC goes soft and even oozes out from under the fondant at the bottom!

I use the upside down method for both ganache and IMBC with pretty good success.

So I guess you're going to tell me I need a crusting buttercream. Is that right? I'm English living in California, so buttercream is pretty new to me. How easy is to get nice smooth fondant on top? How does it stay hard if it doesn't have butter in it, or should I be looking for a butter/shortening recipe?

I would love your recipe ideas and advice!
Many thanks in advance.

I use Indydebi`s buttercream under fondant, If im not useing ganache.

http://cakecentral.com/recipes/6992/indydebis-crisco-based-buttercream-icing

Thank you! How long does it take to crust? And what sort of texture should I expect?

I hardly ever use american buttercream (shortening or butter/shortening) under fondant. If I have to, i'll do an all butter american and make sure it is rock hard from the fridge. but really, I'm stuck on ganache under fondant. it's the best for my climate.

For my non-chocolate fondant cakes, i use a white chocolate ganache. the ratio in weight is 3:1 instead of 2:1 for the dark chocolate.

I also use Indydebi's bc. It doesn't crust super fast, so you have plenty of time to get it all smooth and just right, but usually very shortly after I get it looking just the way I want, it's crusted. I'd say half an hour tops, but probably closer to 20 min. Just be sure your cake is completely cooled or brought to room temperature before covering. You can add more milk or more sugar to get it the consistency you want and I use Sharon Z's method of covering a cake and the it comes out super smooth. HTH