So on Wednesday I'm making a two tier cake for my hubby's 30th birthday. Square on bottom, round on top, covered in fondant.

I live in a super small town and can't find the right size pan(s). I have a 9" round pan but no square. Here's my question.
Can I bake it in a sheet pan and cut it into a square? Will this make it less stable? I do know that it needs dowels.

I'm new to all this but *have* made a couple other fondant cakes. I have used cake mix for the others. Any advice is appreciated!

yes, you can cut squares out of the rectangular sheet cake. Not a problem. Freeze it before you crumb coat it though, or you'll be getting the crumbs from the cut edges everywhere.

Thank you so much!