Can you half this recipe? If so what size pan would be best? Thanks

I'm quite sure the recipe would half successfully, although the baking time will be shorter.

Let's do the math: The recipe calls for a 9 x 13 pan, or 117 square inches. Half of that is 58.5 square inches.

An 8" x 8" square pan is 64 square inches. So (allowing for rounding) is a A 9" round pan. Close enough.