AMy son wants a ice cream filled cake, it'll be my first. My question is "what is the best buttercream to cover cake" seeing it will be in the freezer for some time. Thanks all!

Best options for covering an ice cream cake:

Poured ganache.  It has more cream relative to chocolate than regular ganache, and it will cut OK while frozen.

Whipped cream.  Again it can be cut while frozen.

Rich's Bettercreme if you can get it.  Same reason.

You will have trouble adding a fondant cover.  Better plan to just add fondant cutouts and other loose decorations at the last minute.

AThanks BakingIrene, this is very helpful. Just one more question if you don't mind, is Rich's Bettercream the same as Pastry Pride? Thanks again, I never thought of using poured ganache, which I think I'll use.

Hi - I just joined Cake Central as I also got a request from a friend to make an ice cream cake for her daughter's birthday. I've never made ice cream cake before neither had I tried one myself. I read that oil-based cake works better than butter based cake as the latter will be dry after you freeze it but oil-based cake would be more moist. They prefer lighter fluffy cake so I am also wondering if sponge cake would work better. Anyone has tried either one? Thanks. 

Oh also I just read above that poured ganache, among other things, would work better for frosting as opposed to fondant. I appreciated this being pointed out so I'll make sure I don't use fondant. The poured ganache intrigued me though. Would the slightly warm temperature of the ganache melt the ice cream in the cake when you first pour it over to frost the cake? Thanks.

Many years ago I worked at a Baskin Robbins making ice cream cakes. They came pre-formed in some basic flavors, but for custom flavors we would use a mold (could be any cake pan) and fill it with slightly softened ice cream, leaving room at the top for the cake layer. We would top the ice cream with a thin layer of cake, maybe about half to an inch think. I'm not sure what kind they used (oil versus butter) since it came pre-made. We would freeze the ice cream cake until set then dip the mold in warm water to loosen and flip on to a board.

To frost it we would soften vanilla ice cream and give a good mix in a Kitchen Aid to whip it up a bit. Then we would use the ice cream to "frost" the cake. We usually had simple buttercream on hand in different colors to do the borders and piping so you could probably use your favorite decorators buttercream. I've tried making ice cream cakes at home a couple of times, but not for a while. I was able to get the softened vanilla ice cream to work well as the frosting, but if you would rather frost the entire thing in buttercream it would probably work too. I think Ganache would be hard since it will start to set as soon as it hits the cold ice cream, and if you make the ganache too hot it might melt the ice cream. 

Jennifer - Thanks for sharing your professional ice cream cake experience. That sounds interesting to actually pipe the ice cream onto the cake layer. I actually don't eat ice cream that often so have a question about softening ice cream. To get to the consistency to be able to pipe it don't you have to sort of melt the ice cream? But then once you "melt" it does that change the flavor or texture after you re-freeze it? I just want to make sure the ice cream will still taste fresh and good if I do so...It's for a sweet girl's 10th birthday I just want to make sure that's something memorable for her and her family :-)