Just how oh how do you torte a sheetcake bigger than a 9x13 without making a huge mess out of it???

Use a cookie sheet to lift the top part off. That's what I do. Just be careful and it will all work out. Hope this helps.

you can also use a cake board and an extra set of hands is always helpful too.

I freeze my cake slightly, then cut, then run another board under the cut, and lift off, I keep it cold until I put my icing on the bottom cake, then bring my other out and slide onto the the bottom cake. If the cake is cold it will adjust easier if you don't get it lined up the first time.

I know a lot of people don't like it, but I've have good results with my wilton leveler even with a 9x13, I wait until the cake is completely cooled.