I am making bars for "Teacher Appreciation Week" at work.  And I was wondering if I would need to double a 9x13 recipe for a 15x10 pan or if I could just use the 9x13 recipe?  I think that with the height differences I would be okay to just use a 9x13, but I want to be sure before I start baking after work today!  Thanks in advanced!

According to my handy-dandy Wilton Servings chart, the batter amount difference between a 9x13" and a 11x15" is 1 1/2 cups (10 cups of batter for the 9x13; 11 1/2 cups of batter for the 11x15").  So using the 9x13"-sized recipe in a larger pan will result in a thinner bar.  Maybe scale the recipe up a bit?  Doubling it might be too much, so maybe increase it by a third?

Good luck!

Thank you for your reply.  I was able to find a recipe that called for a 11x15 jelly roll pan.  WHOOO for the internet! :-P .. I will keep this in mind the next time I have this dilemma!