Hi al!  The largest sheet cake I've baked so far has been an 11 x 18, but am getting ready to bake one larger.  I've noticed that at 350, the edges get too done, while the middle takes forever to cook through! How should I adjust my cooking time to get a more evenly baked cake? I'm thinking a lower cooking temp? Any advice would be appreciated. Thanks! 

I like to turn the oven down to 325 for 12 x 18 cakes and increase the time. It has worked well for me. Good Luck.

Love2bake910,

Approximately,  how many minutes do you keep the 12 x 18 cake in oven while cooking at 325?

It has varied, I start at 45 minutes and gauge from there. That's usually close to done for me.

Thanks all. I'll try that! It's for a soldier's promotion, so I want it to be perfect :)