Do you trim each side of the cake before buttercream and fondant? I've watched some youtube videos on covering a square cake with fondant but I was wondering if anyone had any good tips. Do you freeze the cakes before putting the fondant on? I've only done 1 square cake with fondant and the corners were very rounded. Is almost seemed like the fondant was weighing it down or something. Thanks for any tips!

The secret to those Planet Cake SUPER SHARP EDGES is the thickness of the fondant (and the perfectly smooth sharp edge ganache underlay )

If your fondant is any thicker than about 1/8th of an inch you will get rounder edges

I use two large acrylic smoothers as well - one pressing down on the top and one pressing in at the side (with the same amount of pressure) - where they butt up will form a nice sharp edge.

You might try these Prestige sharp edge smoothers

http://www.globalsugarart.com/product.php?id=19558&name=Sharp%20Top%20Edger%20by%20Edgers

I've found these useful for Mini cakes - but still resort to my large smoothers for normal cakes

Do you use MMF?

I recently found that by putting the bc right up to both sides(points) equally that it has helped my square cakes quite a bit, but that edge smoother looks like that will help the rest of the way!

No, I don't use MMF - I use Bakels prepared Pettinice Fondant

You might want to try Susan Zambito DVD it's realy good takes you thru it step by step.