I used a 9 x 13″ pan, and what I did was exactly the same recipe here except I incorporated a cooking technique I read on other recipes online. I started at preheated oven at 350 degrees for 15 minutes, then reduced it to 300 for another 38 mins only because I miscalculated the timing. But it turned out perfectly, with the exception that the edges of the pan were a bit crisp, but still chewy and not at all burnt. A toothpick inserted in the center came out clean even while the center still looked a bit moist. I cooled them then chilled them in the fridge for 40 minutes before slicing.

Thanks for the recipe! Yum!