Make your cornbread batter just as you normally would
I found that a normal cornbread batter recipe fits two 9" pans perfectly. Divide the batter between the pans and place the pans into the cooking rack.
Lower rack into the Big Easy.
Start checking for doneness (particularly on the lower pans) after the usual cornbread cooking time, 15-20 minutes. Check for doneness by inserting a toothpick into the center of each pan. If the toothpick is clean when you remove it the cornbread is done. Note: You might have to remove some pans before others.