And duh, of course you can use a round plate under a square cake. I did that for years before Bakerycrafts started making square plates.

How do you secure your cake circle (cardboard or whatever your cake is actually only) to the plate in the SPS?

I use straws, they are much easier to cut than dowels. I used them in this cake and it was sat at the reception site for 6 hours before it was cut. the pic is just before they cut it. They held up great!

HTH!

http://www.cakecentral.com/cake-photo_1088103.html

Diane,
The SPS plate has a peg that sticks up and fits into the hole that you punch in your cardboard cirlce. I also use a smear of bc.