Hi, I'm just about to build a minion cake, but I'm not sure how to handle covering the layers. It'll be two cakes tall , each on a cake board with dowel supports,then a dome on top; then I'll cover the entire structure with fondant . My issue is as  the bottom and middle layer won't have fondant on top of them, will they be dry?  Should I buttercream each layer all over before assembling, or put a layer of fondant between each layer? Any help would be appreciated!  

ATwo 4" double layer cakes tall? Or are you separating each layer with a board and dowels? I think dowling and boarding a 2" cake is a little much. When stacking cakes, I frost and fill each individual cake as a unit, dowel and place cardboard on top, then place my next filled/frosted cake on top, etc.

I've recently done a number of minions, and I did what you are planning to do.  I did ice the tops of each double-layer cake, sprinkled with powdered sugar to prevent the cakeboard above from sticking entirely, doweled, then set the next cake (with cakeboard) on top.  Once all together, I stuck a skewer down through the entire thing, then put the fondant on.  I used 2 double-layer 6"rounds with a round on top.  I've also used 2 double-layer 8" with a round on top. I actually made a minion on top of a minion using both of these sizes, so it ended up being 4 double-layer cakes.  Then the top minion was holding a cupcake above his head.  It was very tall!

Thank you for your replies, all done now with your advice taken on board! Yes it was the deeper cakes for doweling and as the cake had to go on a nerve -racking car journey I was keen to dowel more rather than not enough ....I sometimes wonder why I put myself through this stress but the end result looked great.